Post on 07-Aug-2020
2018 31st Annual Graduate Research Symposium
Tuesday, February 12 –
Wednesday, February 13
2019
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Tuesday, Feb 12
Time Location
Check-in and Breakfast 8:00am – 8:30 EBB CHOA Room
Welcome Talks from Faculty 8:30 – 8:55 EBB CHOA Room
Oral Presentation Session I 9:00 – 10:00 EBB CHOA Room
Keynote Speaker 10:00 – 10:45 EBB CHOA Room
Student/Industry Networking 11:00 – 12:00 MoSE 1st Floor Atrium
Lunch 12:00pm – 1:00 MoSE 2nd Floor Atrium
Poster Session 1:00 – 2:30 MoSE 3rd & 4th Floor
Atrium
Oral Presentation Session II 2:45 – 5:00 EBB CHOA Room
Reception & Student
Networking
5:00 – 6:00 MoSE 3rd Floor Atrium
Dinner 6:00 – 7:30 MoSE 2nd Floor Atrium
Wednesday, Feb 13
Breakfast 8:00am – 8:30 EBB CHOA Room
Oral Presentation Session III 8:30 – 9:30 EBB CHOA Room
Industry Panel 09:40 – 10:20 EBB CHOA Room
Oral Presentation Session IV 10:30-11:30 EBB CHOA Room
Interviews / Lab Tours / Break 11:30 – 12:30 EBB CHOA Room
Lunch & Closing Ceremony 12:30 - MoSE 2nd Floor Atrium
IBB
Marcus
Nanotech
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Contents
Keynote Address ................................................................. 3
3M ................................................................................... 3
Poster Session ..................................................................... 3
Materials and Nanotechnology........................................ 3
Energy and Sustainability.............................................. 11
Biotechnology ............................................................... 14
Oral Presentation Session I ............................................... 16
Materials and Nanotechnology...................................... 16
Oral Presentation Session II .............................................. 18
Materials and Nanotechnology...................................... 18
Oral Presentation Session III ............................................ 22
Energy and Sustainability.............................................. 22
Oral Presentation Session IV ............................................ 24
Energy and Sustainability.............................................. 24
Complex Systems .......................................................... 24
Biotechnology ............................................................... 25
Acknowledgements ........................................................... 27
2019 Graduate Symposium Executive Boards .............. 27
Special Thanks to: ......................................................... 27
Sponsors ............................................................................ 28
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Keynote Address
3M New Materials for the Simplification of Biopharmaceutical Purification Dr. Jonathan Hester / Senior Technical Specialist / 3M Dr. Jonathan Hester has a B.S. in Materials Science and Engineering from Purdue
University and a Ph.D. in Polymer Science from M.I.T. Since 2000, he has had multiple
technical roles at 3M, ranging from basic technology development in 3M’s Corporate Research Laboratory to, most recently, product development in the 3M Separation and
Purification Sciences Division, where he works on the development of liquid separation
solutions for biopharmaceutical processing. Jon is a co-inventor on 22 patent publications related to liquid separations materials, devices, and processes. With specific examples and
discussion of key learnings, Jon’s talk will illustrate how new functional porous materials
can be used to simplify the multi-step process used to purify the therapeutic proteins that are the basis for some of today’s most promising treatments for cancers and other important
indications.
Poster Session
Materials and Nanotechnology
1. A Database of 2D Zeolite Nanosheets: Development and Applications
Omar Knio / Prof. David S. Sholl
Zeolites are nanoporous aluminosilicates widely used in catalysis and separations
applications. Though generally formed as 3D crystals, new synthesis techniques have given
access to 2D zeolite nanosheets with small diffusion path lengths and accelerated molecular
diffusion. Since most previous research has focused on bulk zeolite crystals, there is little
understanding of the surface adsorption and diffusion mechanisms likely involved at such
length scales and their contributions to the permeability and selectivity of different species.
To enable the systematic examination of such surface properties, we constructed a database
of more than 800,000 computation-ready 2D zeolite nanosheets from the full range of
known zeolite structures in the IZA database of zeolite structure types. The nanosheet
surfaces cover a wide range of orientations and were created via the principle of minimizing
the number of bonds broken during the termination of a unit cell. The database consists of
two sets of nanosheets: one set with known heights and unrelaxed surfaces, and another set
with arbitrary heights and relaxed surfaces.
As an initial example of the utility of this database, we generated equilibrium Wulff shapes
for 203 3D zeolite structure types in the International Zeolite Association (IZA) database.
Since our database is pure silica, our predicted crystal shapes resembled experimentally
synthesized crystals with high Si:Al ratios. Finally, we used Molecular Dynamics to
identify zeolite nanosheet properties ideal for the industrially relevant separation of H2
from CO2. To that end, we examined the surface contribution to diffusion as a function of
slab height in MFI, a widely used zeolite. By incorporating surface effects, the current
study lays the groundwork for high throughput screening of zeolite nanomaterials in their
thinnest and most promising form.
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2. Selective CoAxial Lithography via Etching of Semiconductors
(SCALES): A Bottom-up Nanoscale Patterning Process for Very Large-
Scale Electronic Device Manufacturing
Amar Mohabir / Prof. Michael Filler
Nanoscale electronic devices, such as field effect transistors, contain one or more features
with nanoscale dimensions. When such devices are to be produced at very large
manufacturing rates (e.g., for large-area integrated circuitry), a bottom-up alternative to
top-down patterning is necessary to define these features. Here, we show how surfaces with
regions of differing composition can be selectively masked using surface-initiated growth
of polymer films. Our approach is particularly useful for patterning semiconductor
nanowires where composition is modulated along the nanowire length. Surface masking is
accomplished in a two-step procedure. (1) Atom transfer radical polymerization (ATRP)
of polymethylmethacrylate (PMMA) first occurs from a surface-tethered initiator in a
blanket fashion, covering all surfaces regardless of composition. (2) A subsequent selective
etch removes the polymer only from regions whose underlying surface is susceptible to the
etchant. We apply this technique, dubbed Selective CoAxial Lithography via Etching of
Semiconductors (SCALES), to nanowires containing axially-modulated doped/undoped Si
and Si/Ge regions. For the case of doped/undoped Si nanowires, KOH removes PMMA
from the undoped regions but does not attack the doped regions. For the case of Si/Ge
nanowires, PMMA is removed from the Ge regions by etching with H2O2 but remains on
the Si regions. We investigate the role of surface pre-treatment, PMMA polymerization
parameters, and post-polymerization etching on the SCALES process with a suite of
spectroscopy and microscopy techniques. The ability to mask nanoscale objects in a
bottom-up fashion opens up the possibility of nanoscale patterning in a truly scalable
manner.
3. Synthesis and Properties of Degradable Polyaldehyde Copolymers
Anthony Engler / Prof. Paul Kohl
Polyaldehydes are metastable materials at ambient conditions due to their typically low
thermodynamic ceiling temperature (TC), or the equilibrium temperature between
monomer and polymer. Breaking one backbone bond in the polymer above the TC will
initiate total depolymerization down the polymer chain, converting back to aldehyde
monomer. Polyaldehydes have yet to find a robust application in materials, because of their
instabilities at ambient temperatures. Rather than a drawback, the low TC phenomenon
offers a unique advantage in the degradation of polymers due to the minimum activation
energy required to degrade an entire polymer chain. This ability to rapidly convert to small
molecules makes polyaldehydes well suited for applications in stimuli-responsive
materials, transient technology, and sacrificial materials. Novel copolymers were
synthesized using a variety of aliphatic and functional aldehydes with o-phthalaldehyde,
which provides high molecular weight and stability. Reactivity behavior of aliphatic
aldehydes correlates positively with the aldehyde’s hydration equilibrium constant (KH),
with electron-deficient aldehydes incorporating into copolymers at higher percentages.
Higher incorporations of aliphatic aldehydes bring about lower molecular weight
polymers. The polymerization is tolerant to chain length, branching, non-conjugated
unsaturation, halogens, and sulfonate esters. Post-polymerization modifications are
performed to introduce inaccessible functional groups like epoxy, thioethers and azides.
Applications towards transient technology are discussed.
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4. Commercialization Strategies for Renewable Multilayer Chitin
Nanofiber and Cellulose Nanocrystal Barrier Films
Chinmay Satam / Prof. Carson Meredith
Petroleum derived plastics are a huge environmental concern today due to their low
biodegradability combined with the increased environmental impact associated with the
use of petroleum. Of particular concern is the accumulation of waste plastics in oceans and
landfills, which causes environmental, land management and logistical problems. In 2018,
we developed a 100% bio-based composite barrier material by spray coating chitin
nanofibers (ChNFs) and cellulose nanocrystals (CNCs) onto poly(lactic acid) (PLA). The
resulting flexible film had similar barrier properties to poly(ethylene terephthalate), but
with the added benefit of renewability and compostability. In addition to this work, we
investigated blended ChNF and CNC films using chitin with different degrees of
acetylation. We found that films produced by using deacetylated ChNFs not only had better
barrier properties but also, when blended with CNCs, required less ChNFs to achieve
comparable barrier properties. In addition, we developed a process to manufacture ChNFs
that reduces the cost of production by 40 % but at the same time improves the mechanical
properties of the resultant neat solution cast films. These developments bring the spray
coated ChNF-CNC multilayer films closer to commercialization and towards replacing part
of the plastics in food packaging with more renewable materials that are compostable and
can be produced in a circular manner.
5. Vapor Phase Infiltration of Metal Oxides into Microporous Polymers for
Solvent Stable Nanofiltration Membranes
Fengyi Zhang / Prof. Ryan P. Lively / Mark D. Losego
Owing to their high surface area and hierarchical porosity, microporous polymers, such as
polymers of intrinsic microporosity (PIMs), have shown great potential in heterogeneous
catalysis, adsorption, and membrane separations, among other applications. Linear
microporous polymers (e.g., solution-processable PIM-1), can be easily manufactured into
form factors consistent with large-scale separations (e.g., hollow fibers). However, the
limited organic solvent resistance of linear microporous polymers restrict their application
in aggressive operating environments. Two of the most prominent post-fabrication
methods for improving the stability of polymers are pyrolytic carbonization and
crosslinking. These are both promising approaches to rigidifying polymeric materials, but
require a near-complete transformation of the precursor in the former case and
chemical/thermal treatments in the latter case.
Here, we develop a novel post-fabrication modification technique for improving the
stability of microporous polymers without damaging the microstructure and macroscale
form factors. Cyclic vapor phase infiltration of metal-organic precursors and water into the
structure of PIM-1 creates monolayers or bilayers of sub-nanometer metal oxide structures
on the surfaces of the interconnected PIM-1 micropores. The resulting interpenetrating
atomic-scale networks of metal oxide and PIM-1 retain the microporosity and exhibit
excellent solvent resistance to strong solvents for PIM-1 (chloroform, dichloromethane,
and tetrahydrofuran). While PIM-1 membranes cannot effectively reject polystyrene
oligomers below 1200 g/mol from ethanol, the hybrid PIM-1 membranes reject polystyrene
oligomers larger than 400 g/mol. Besides, the interpenetrating aluminum oxide networks
inhibit the interaction between membranes and solutes, increasing the Rose Bengal
rejection from 45% to 86%. Since the vapor phase infiltration process can be directly
applied to state-of-art membrane modules, this treatment has the potential to be adopted
into the large-scale manufacturing of advanced membranes.
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6. High swing capacity MIL-101(Cr) fiber sorbents for sub-ambient CO2
capture via RCPSA
Stephen J.A. DeWitt / Prof. Ryan P. Lively
A challenge facing CO2 capture from flue gas via adsorption is the high cost of adsorbent
materials, a phenomenon partially driven by low operating capacities leading to massive
sorbent requirements. Increasing operating capacity can be accomplished by advances in
sorbent materials, cycle design, and process design, giving the sorbent more capacity or
making it operate more efficiently. This talk focuses on designing new structured sorbents
using metal organic framework (MOF) materials to enable high capacity via a sub-ambient
rapidly cycled pressure swing adsorption (RCPSA). We have found flue gas compression
and cooling is counterintuitively energy efficient when extensive heat integration and
energy recovery is utilized, and this concept enables high operating capacity for a variety
of MOF sorbents. Current technoeconomic estimates reveal parasitic loads as low as 19%
and total costs of CO2 as low as 37$/tonne.
In this talk, after a brief review of the sub-ambient RCPSA process flow sheet, we will
discuss methods of incorporating MIL-101(Cr) into fiber sorbent contactors via direct
spinning. Sub-ambient CO2 isotherms show MIL-101(Cr) may be capable of swing
capacities as large as 10 mmol/g, making it an ideal material for sub-ambient RCPSA.
Incorporating this material into a fiber sorbent contactors make possible order of magnitude
lower pressure drops as well as enabling thermal management, which increases sorbent
utilization. The talk will focus on the application of these fibers to capturing CO2 from
simulated flue gas, and will include analysis of breakthrough curves and cyclic stability of
the sorbent. These fiber sorbents containing high operating capacity sorbent materials help
to support the case for applicability of the novel process design.
7. Evidence for entropic diffusion selection of xylene isomers in polymer
derived carbon molecular sieve membranes
Yao Ma / Prof. Ryan P. Lively
The purification of benzene derivatives, particularly xylene isomers, is one of the most
important organic mixture separations practiced in industry. The separation of xylene
isomers is especially challenging due to the similarity of their physical properties. Carbon
molecular sieve (CMS) membranes are promising materials for such challenging solvent
separations due to their thermal and chemical stability, but these materials have not been
studied in detail in the case of large organic molecules. Xylene isomer transport and
sorption properties in a CMS membrane derived from a prototypical polymer of intrinsic
microporosity (PIM-1) reveal that diffusion selectivity is the dominant factor in
contributing to the preferential permeation of p-xylene over o-xylene. Moreover, the
contributions of “enthalpic” and “entropic” selectivity to the diffusion selectivity are
studied in detail and reveal that entropic factors dominate the xylene selection mechanism.
Overall, this study provides fundamental insight and guidance into the separation of large
organic molecules in amorphous microporous materials.
8. Effects of acid gases in chemically stable metal-organic frameworks
Eli Carter / Prof. Krista S. Walton
Metal-organic frameworks (MOFs) are promising materials for a variety of applications,
including adsorption separation processes. Some of these potential gas separation
applications involve exposure to acid gases (e.g. sulfur dioxide and nitrogen oxides), which
may cause framework degradation or poisoning of adsorption sites, limiting the
applicability of MOFs in adsorption processes or making their repeated use more difficult.
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In this work, MIL-101(Cr)—a chemically stable MOF predicted in literature to experience
poisoning by acid gases and derivatives—is exposed to SO2 and NO2 at varying
concentrations under both dry and humid conditions. Post-exposure nitrogen physisorption
measurements demonstrate a loss of adsorption capacity—as measured by BET surface
area—caused by exposure to SO2 and NO2, but without structural degradation (as
indicated by powder x-ray diffraction). Repeated single-component breakthrough
experiments (with sample regeneration conducted in situ) done with both SO2 and NO2 on
MIL-101(Cr) show that this loss in adsorption capacity applies to multiple adsorbates and
cannot be completely reversed by normal activation conditions. X-ray photoelectron and
infrared spectroscopy conducted post-exposure and after regeneration conditions show
retention of acid gas species and their derivatives in the MIL-101(Cr) samples, suggesting
that the cause of the reduced post-exposure capacity includes acid gas species strongly
bound to the framework structure. These results experimentally confirm a difficulty that
acid gases may present in MOF adsorbents in addition to well-known issues of chemical
stability. Hence, the results draw attention to a detrimental effect of acid gases to be
accounted for in future work on chemically stable MOFs.
9. Porous MOF-Polymer Composite Fibers by Solution Blow Spinning
Jacob Deneff / Prof. Krista S. Walton
Nonwoven polymer composites containing metal organic frameworks (MOFs) as active
materials have shown promise as protective textiles and adsorbents. Solution blow spinning
(SBS) is a recently developed technique for nanofiber production that represents an
alternative to electrospinning. SBS uses high velocity gas to draw polymer solutions
through a nozzle, forming fibers upon solvent evaporation. It is capable of producing fibers
with the same diameter range as electrospinning, but with higher throughput and requiring
no specialized solvent or electrical field, making it attractive for scaled-up and in-situ
applications. By suspending MOF in the polymer solution before spraying we can produce
MOF-polymer composites combining the structure and mechanical stability of nonwoven
textiles with the adsorbent and catalytic properties of MOFs. Additionally, by incorporating
non-solvent into the spray we can create porosity through phase separation, ensuring that
the active material is accessible within the polymer matrix. These composites can be
applied in-situ for personal protection and detoxification of industrial chemicals and
chemical warfare agents.
10. Facile Integration of Porous Nanomaterials on and from Support Media
Jayraj N. Joshi / Prof. Krista S. Walton
Unconventional strategies for synthesizing advanced separation materials can reduce
manufacturing complexity while affording economic and environmental benefits.
Accordingly, we present a novel method for producing supported porous nanomaterials
both from and on aluminum-based support structures. Supported MOF composites are
created in one-step from inexpensive aluminum oxides, alloys, meshes, foil, and even
recycled beverage cans. Microscopy reveals uniform monolayer epitaxial MOF growth.
The same strategy is adapted to different framework systems, as well as non-supported
adsorbent production with unique textural properties. Scaffolded microneedle MIL-53(Al)
MOFs produced from this study are additionally ideal precursors for creating supported
aluminum oxide nanotubes. Through MOF pyrolysis, micro/mesoporous alumina
structures emerge 1-5µm perpendicular from the underlying support. In addition to the
conventional uses of alumina as catalyst and adsorbent supports, newly-generated oxides
investigated here afford unique MOF regrowth and acid gas remediation applications.
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Presented findings establish a simple and accessible gateway for building nanoscale-
controlled devices, hierarchical separation media, and high performance membranes.
11. Comprehensive Study of SO2 Adsorption in a Series of Metal-organic
Frameworks
Julian Hungerford / Prof. Krista S. Walton
A series of Metal-organic Frameworks (MOFs) were synthesized and SO2 adsorption
isotherms were collected on a lab build pressure decay apparatus to develop structure-
property relationships. The MOFs tested included: DMOF-TM, DMOF-ADC, MIL-
53(Al), Cu-BTC, UiO-66, MIL-101(Cr), ZIF-7, ZIF-8, ZIF-11, and ZIF-65. All MOFs
used in this study were found to be stable upon exposure to SO2 for the duration of the
isotherm collection. We established that MOFs with larger pore volumes correlated with
higher SO2 adsorption capacity at high SO2 pressure. MIL-101(Cr) had the highest SO2
adsorption capacity of 21 mmol/g while also having the largest pore volume of 1.3 cm3/g.
MIL-53(Al), Cu-BTC, and ZIF-65 displayed similar SO2 adsorption capacities of roughly
12 mmol/g while having similar pore volumes. ZIF-7 and ZIF-11 adsorbed very little SO2
at all adsorption points, these materials have pore diameters smaller than the kinetic
diameter of SO2 and we hypothesize that any SO2 adsorption is likely due to structure
defects or linker flexibility. When analyzing the low pressure region of the SO2 adsorption
isotherms for these MOFs a different relationship is observed. Cu-BTC, a MOF containing
open metal sites (OMS), displayed strong SO2 adsorption at the lowest adsorption points.
DMOF-TM does not contain OMS, however it displayed greater low pressure adsorption
than Cu-BTC. The pore diameter of DMOF-TM is nearly identical to the kinetic diameter
of SO2 such that molecular sieving may contribute to a large SO2 adsorption at low
pressure. Our overall findings show that MOFs with the large pore volumes will have large
SO2 adsorption capacities at high pressures, while OMS or molecular sieving dominate the
low pressure region.
12. Rheological Characterization of Nanocellulose Materials for Quality
Control
Jianshan Liao / Prof. Victor Breedveld
Nanocellulose material is a renewable and sustainable nanomaterial produced from
abundant cellulose sources. Its high strength and biodegradability make it attractive to
many applications such as composites, coatings and rheological modifiers. To ensure
consistent production of high quality nanocellulose materials, one of the most urgent issues
to be addressed is the lack of standardized, rapid and reliable characterization methods.
Current techniques, such as electron microscopy and light scattering, are expensive and
time-consuming. Moreover, they only probe a small portion of the nanocellulose sample,
which may misrepresent the sample’s bulk properties. Rheology provides a fast and cost-
effective way to characterize nanocelluloses in large volume. In this work, we will show
the influence of concentration and salt content on rheological properties of cellulose
nanocrystal and TEMPO oxidized cellulose nanofiber. A rheological model was
formulated to capture the viscosity across shear rates and concentrations. We will also
demonstrate the change of fiber length and carboxylic content of cellulose nanofiber
reflected on the change of their rheological properties, which can be captured by the
rheological model.
13. The Geode Process: A Route to the Large-Scale Manufacturing of
Functionally-Encoded
Maritza Mujica / Prof. Victor Breedveld / Prof. Michael Filler
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Future large-area electronic and photonic technologies will require the manufacturing of
materials and devices at very high rates without sacrificing nanoscale control of structure
and composition. Semiconductor nanowires can be produced with exquisite spatial control
of composition and morphology using the vapor-liquid-solid (VLS) mechanism that,
unfortunately, remains limited to very small manufacturing rates. Here, we introduce the
Geode process to synthesize functionally-encoded semiconductor nanowires at
throughputs orders of magnitude beyond the state-of-the art. Central to the Geode process
are sacrificial, porous-walled, seed particle-lined silica microcapsules, whose interior
surface serves as a high-surface area growth substrate. Microcapsules protect the growing
nanostructures, are produced with a scalable emulsion templating technique, and are
compatible with large-scale chemical reactors. We will show how microcapsule structure
and drying is influenced by silica nanoparticle type and concentration, emulsification
parameters, and nanoparticle cross-linking agent. We will also demonstrate the synthesis
of Si nanowires with programmable dopant profiles on the microcapsule interior, which
not only shows the versatility of the process, but also allows the impact of precursor gas
transport limitations to be characterized.
14. Control of Nucleation Density in Conjugated Polymers via Seed
Crystallization
Michael McBride / Prof. Martha Grover
Desired semiconducting electronic properties of conjugated polymer systems are highly
dependent on the thin film morphology. The requirement of interconnected assemblies has
been deemed most influential for long range percolative charge transport. However,
entanglement effects in conjugated polymers severely limits the π stacking of polymer
chains into interconnected crystalline domains. The entanglement of individual chains can
be reduced through solution processing methods that promote the nucleation and growth
of tightly packed, ordered structures.
Herein, we demonstrate facile solution processing methods to target the formation of
interconnected assemblies. Poly(3-hexylthiophene) (P3HT), the canonical semicrystalline
conjugated polymer to investigate the mechanism of self-assembly in solution, was utilized
as a representative model polymer. Manipulation of the polymer molecular weight
distribution, solute-solvent interactions via solution environment, and quantity of seed
nuclei are shown to be tunable parameters impacting the degree of interconnectivity during
self-assembly. Both the generality and limitations of these approaches were investigated
using a wide array of nucleation events including exposure to low dose UV, microfluidic
flow processing, and poor solvent addition. A particularly promising approach involves the
selective mixing of a nucleated polymer solution with a non-nucleated sample.
Mechanistically, highly crystalline and order domains can be formed during primary
nucleation and then interconnected via secondary nucleation. These processing approaches
have improved the charge carrier mobility from a base of ~10-3 to exceeding 0.200 cm2/V-
s.
General process-structure-property relationships were developed to quantitatively describe
the tradeoffs between polymer network formation and grain boundaries on charge
transport. All examined cases suggest an optimal processing window for long range
interconnectivity.
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15. Enhanced electrical conductivity of polyacrylonitrile (PAN) fiber with
reduced amount of carbon
Mingxuan Lu / Prof. Satish Kumar
Carbon nanotubes (CNT) have gained much attention and interest to be used as
reinforcement material because of their extraordinary mechanical, electrical, and thermal
properties. Previous literature reported that introduction of high loading (15 to 20 wt %)
CNT into polyacrylonitrile (PAN) fiber enhanced electrical conductivity of polymer matrix
and enabled multifunctionality such as Joule heating effect. Joule heating can potentially
reduce energy cost of producing carbon fibers from PAN precursors compared to
traditional heating by convection oven. Recent research work is aimed to reduce CNT
amount in fibers while maintaining good electrical conductivity of PAN/CNT fibers. Core-
sheath structure was used, and highly percolated CNT (10 wt %) was put into a thin sheath
only for enhancement of electrical conductivity. PAN/PAN-CNT core/sheath fibers were
successfully made with different core-sheath area ratios. The overall CNT content in fibers
was in the range of 3.7 – 6.6 wt %. Electrical conductivity of as-spun fibers with low crystal
size and crystallinity was improved with short-time annealing or slight drawing, when
CNTs had more chance to rearrange themselves to form increased number of percolation
pathways. Slightly drawn fiber (3x draw ratio) of 4.4 wt % CNT possessed electrical
conductivity of 0.38 S/m before annealing and up to 5 S/m after annealing. The tensile
strength and modulus of corresponding fibers were as high as 299 MPa and 12.7 GPa,
respectively. These fibers will be used to verify Joule heating effect in the future. Also, we
believe these fibers can enable new applications with the combination of electrical and
mechanical properties.
16. Engineering cellulose nanomaterials as alternative supports for
heterogeneous cooperative
Nathan Ellebracht / Prof. Christopher W. Jones
Cellulose nanomaterials (CNMs) are a class of advanced bioproducts being investigated
for a range of applications. The hydroxyl-rich surfaces of these cellulosic biomass-derived
crystalline nanomaterials are excellent substrates for chemical functionalization, and their
fibril-like structures allow them to assemble as foams, films, hydrogels, and aerogels. The
unique properties of these adaptable materials have led to investigations for an array of
specialty applications including sensing, separations, and catalysis. Studies of CNMs as
catalyst supports have focused on supported metal nanoparticles in homogeneous
suspensions. Poor thermal and chemical stability pose significant limitations to the range
of catalytic applications possible for CNMs, but their ability to form structured porous
materials like aerogels offers unique opportunities in catalysis.
Co-located organic acid and base surface species, typically studied in silane-modified
silicas, can function as enzyme-inspired cooperatively catalytic active sites. Cellulose
nanomaterials as demonstrated herein as an alternative to these well-studied porous
inorganic supports for heterogeneous organocatalysis. Dual acid and base character was
imparted to CNM surfaces through controlled chemical functionalization, and these
multifunctional materials were demonstrated as viable acid-base catalysts for aldol
condensation reactions. Aspects of surface chemistry determining catalytic were probed
and optimized through quantitative control of various surface species. As cooperative
catalysts, the relative abundance and spacing of acid (COOH) and base (NH2) species were
demonstrated to be key determinants of catalytic activity. The crystalline nature of CNMs
allowed for precise understanding of the order and proximity of catalytic species, resulting
in catalysts which outperformed state of the art aminosilica catalysts in both activity and
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selectivity. Effective catalysis toward desired products in upgrading reactions of biomass-
derived furfural was demonstrated with optimized CNM catalysts. Finally, porous solid
aerogel CNM catalysts were developed for biomass upgrading catalysis in batch and flow.
17. Silica Supported Sterically Hindered Amines for CO2 Capture
Jason J. Lee / Prof. Christopher W. Jones / Prof. Carsten Sievers
Most studies exploring CO2 adsorption on solid supported amines have focused on simple,
sterically unhindered amines or alkylimine polymers. It has been observed in extensive
solution studies that another class of amines, namely sterically hindered amines, can give
enhanced CO2 capacity when compared to their unhindered counterparts. While sterically
hindered amines have been well studied in solution, there has been limited research
conducted on this amine type on solid supports.
In this work, the CO2 adsorption performance of mesoporous silica materials
functionalized with hindered amines are investigated using fixed bed breakthrough
analysis. Furthermore, chemisorbed CO2 species formed on the sorbents are elucidated
using in situ FTIR and NMR spectroscopy. Enhancement of CO2 adsorption capacity is
observed for all supported hindered amines under humid conditions and this increase in
capacity is in part due to the formation of ammonium bicarbonates. Our experiments also
suggest that chemisorbed CO2 species formed on supported hindered amines are weakly
bound, which may lead to reduced energy costs associated with regeneration.
Energy and Sustainability
18. Selective Removal of Hydrogen Sulfide from Biogas Streams Using
Sterically Hindered Amine Adsorbents
Claudia N. Okonkwo / Prof. Christopher W. Jones
Sterically hindered amines in solution have been explored for H2S capture and they have
been found to be selective for removing H2S over CO2 compared to the conventional
methyl diethanolamine (MDEA) or unhindered amines. A disadvantage with these amine
solutions is the high regeneration energies required while operating practical, aqueous
systems. As a result, the use of solid supported materials with lower heat capacities and
improved energy costs has been proposed. This work uses sterically hindered amines on
solid supported materials to determine their H2S selectivity in the presence of CO2 and
CH4. Using a breakthrough apparatus, in-situ infrared spectroscopy and thermogravimetric
analysis we have investigated (i) the H2S selectivity in a multicomponent gas mixtures, (ii)
the nature of the chemisorbed species formed during H2S adsorption and (iii) the effect of
concentration and temperature on H2S adsorption performance on these sterically hindered
amine adsorbents under dry conditions.
19. Fabrication of AEL zeolite nanosheet membrane on alumina hollow
fibers for molecular-sieving applications
Akshay Korde / Prof. Sankar Nair / Prof. Christopher W. Jones
Two-dimensional zeolites are promising materials for the fabrication of ultra-thin zeolite
membranes that show high flux and separation efficiency as demonstrated for MFI zeolite.
Several other zeolite frameworks have been crystallized as a multi-lamellar stack of two-
dimensional nanosheets but their fabrication into membranes for separation applications
still remains unexplored. In this work, two-dimensional AEL nanosheets are used to
fabricate thin AEL zeolite membranes on the shell side of alumina hollow fibers to
demonstrate a proof of concept for scalable zeolite membranes that can display molecular-
sieving abilities. The multi-lamellar AEL nanosheets are exfoliated through polymer melt
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compounding with polystyrene. Exfoliated AEL zeolite nanosheets are then vacuum coated
on the shell side of alumina hollow fibers followed by a secondary growth step to form a
continuous membrane layer that is ~2 µm thick. These membranes are then activated
through exposure to a high intensity UV lamp and their molecular-sieving ability is
demonstrated through single-component vapor permeation of several organic molecules
that cover a wide range of kinetic diameters.
20. Kinetics of CO2 adsorption in amine-functionalized materials with
stepped isotherms
Trisha Sen / Prof. Yoshiaki Kawajiri / Prof. Matthew J. Realff
CO2 uptake in amine-functionalized MOFs, such as Mg2(dobpdc), follows a tunable
stepped isotherm behavior, which enables unprecedented high equilibrium and pressure-
swing capacities for CO2 capture under DAC (Direct Air Capture) conditions (< 0.4 mbar).
This study attempts to move beyond the equilibrium understanding of these materials, by
analyzing their kinetics associated with DAC and to determine whether this limits their
practical application.
An adsorption breakthrough setup with ultra-dilute (0.4 mbar) and dilute (1 mbar, 5 mbar
and 10 mbar) feed was used as a proxy to simulate practical systems. Local equilibrium
theory for stepped isotherms predicts a simple single shock breakthrough for CO2
concentrations above 1% (or 10 mbar). Below 10 mbar, we expect two shocks separated
by a plateau corresponding to the isotherm step pressure. The predicted shapes of the
breakthrough profiles matched the experimentally observed results only qualitatively.
Attempts to fit a traditional LDF mass transfer model to match the observed data were
unsuccessful. While CO2 is simply physisorbed below the isotherm step, a cooperative
mechanism kicks in once this critical loading has been achieved. To capture these kinetics,
a simple LDF model before the isotherm step change and a model for co-operative uptake
(Avrami / Michaelis-Menten) above the step were implemented. Further, quantifying the
CO2 capture fraction of the bed at saturation showed that the bed utilization efficiency is
severely reduced at low feed concentration especially with increasing flowrates.
The aim of this work is therefore two-fold. Firstly, to understand and quantify the system
kinetics of amine functionalized adsorbents with stepped isotherms. Secondly, this study
indicates that moving beyond equilibrium or swing capacity of these adsorbents, and
looking at their kinetics is crucial to assess their efficiency in practical DAC applications.
21. Ethylene/Ethane Separation in Metal-Organic Frameworks by
Computational Modeling
Wenqin You / Prof. David S. Sholl
Metal-organic frameworks (MOFs) with open metal sites (OMS) are known to be selective
for ethylene relative to ethane. In practical applications of this separation, the presence of
other small molecules such as H2O, CO, and C2H2 may affect the suitability of sorbents.
We used density functional theory (DFT) calculations to compute the binding energies of
H2O, CO, C2H2, C2H4, and C2H6 in M-BTC (BTC = 1,3,5-benzenetricarboxylic acid)
with 12 different metals forming OMS (M = Mg, Ti, V, Cr, Mo, Mn, Fe, Ru, Co, Ni, Cu,
and Zn). To probe the generality of these results for MOFs containing other ligands, we
performed similar calculations for metal-substituted MOFs based on four more materials
with dimeric Cu sites. Our results provide useful insights into the variations in binding
energies that are achievable by metal substitution in this broad class of MOFs, as well as
13
pointing towards feasible adsorption-based separation strategies for complex molecular
mixtures. Zn OMS MOFs were predicted to have the highest C2H4/C2H6 selectivity, but
the strong binding energy of solvents and other small molecules in these materials may
create practical challenges. We used DFT calculations to examine whether functionalizing
linkers in these materials with electron withdrawing (-fluorine) and donating (-methyl)
groups offer a useful way to tune molecular binding energies on OMS in these materials.
22. SEPARATION AND PURIFICATION OF BIODERIVED FURANIC
MOLECULES WITH METAL-ORGANIC FRAMEWORKS
Yadong Chiang / Prof. Ryan P. Lively / Prof. Sankar Nair
This work investigates the use of microporous adsorbent materials to purify furanic
products from liquid mixtures generated during processing of lignocellulosic feedstocks.
Furanics are high-value added chemicals since they can be used as biofuels and as
important “platform chemical” precursors to polymers, pharmaceuticals, and fine
chemicals. Conversion of sugars or other feedstocks to furanics often leads to complex
product mixtures in which the components are typically heat sensitive, have similar
physicochemical properties, and form azeotropes, thus making conventional separation
processes such as distillation unfavorable. Such “high-resolution” separations (wherein the
molecules possess very similar characteristics) require approaches based upon precisely
tailored materials as separating agents. MOFs are a group of newly explored microporous
materials consisting of metal ions/clusters coordinated to organic linker molecules. Two
classes of MOFs (i.e., UiO and ZIF) are identified as potential adsorbents for their high
selectivity, capacity, and reusability to develop two new separation processes for the
purification of furfural and 2,5-dimethylfuran (DMF). A suite of characterization and
modeling techniques including single-component adsorption, ideal adsorbed solution
theory (IAST) calculations, multicomponent vapor/liquid mixture breakthrough
experiments, and pulsed-field-gradient nuclear magnetic resonance (PFG-NMR) are used
to build the key structure-property (i.e., adsorption/diffusion) relations. One recent advance
(Chiang et al, ACS Sus Chem Eng, 6, 7931-7939, 2018) is the purification of (DMF) from
n-butanol (BuOH) wherein the separation is limited by an azeotrope formation at 90%
DMF at 1 bar and elevated temperature. Our investigation shows that ZIF-8 (DMF/BuOH
selectivity~5 using 10% DMF feed) and defect-engineered UiO-66 (BuOH/DMF
selectivity= ~8 using 10% n-BuOH feed) adsorbents, when used in series, can upgrade
dilute DMF feeds from 10 wt% to purified (99%+) DMF and also generate a high-purity
(>95%) n-BuOH recycle. A detailed discussion on the re-design of separation using MOF
adsorbents in simulated-moving bed processes with multi-component mixtures will be
presented.
23. In operando optical visualization of Br5- electrochemistry with a planar
glass battery for Zn/Br flow batteries
Yutong Wu / Prof. Nian Liu
Rechargeable Zn-based batteries are a safe alternative to Li-ion for compatibility with
aqueous electrolyte. Also, theoretical volumetric energy density of Zn-based batteries (e.g.
Zn-air) is ~85% of lithium-sulfur battery. However, the performance of Zn anode is limited
by passivation and dissolution. Here we report a ZnO@TiN core/shell nanorod structure
for rechargeable Zn anode. The small diameter (<500 nm) of ZnO prevents passivation and
allows full utilization of active materials, while the thin and conformal titanium nitride
(TiN) coating mitigates Zn dissolution in alkaline electrolyte, mechanically maintains the
nanostructure, and delivers electron to nanorods. As a result, the ZnO@TiN core/shell
nanorod anode achieves superior battery performance compared with bulk Zn foil or
14
uncoated ZnO nanorod anode. It delivers excellent long-term electrochemical performance
(more than 7,500 cycles) as cycled under start-stop conditions. The nanoscale design
principles reported here can potentially be applied to overcome other intrinsic limitations
of Zn anodes and other battery materials.
Biotechnology
24. Engineering Zika Antigens to Enhance Neutralizing Antibody
Responses
Ana Stringari de Castro / Prof. Ravi Kane
Infections with Zika virus (ZIKV) have been linked to the development of serious
neurological conditions like microcephaly and Guillain-Barré syndrome. However, a Zika
vaccine is not commercially available yet. The ZIKV Envelope (E) protein is the main
target of neutralizing antibodies and it can be divided into three domains: DI, DII, and DIII.
Recently, three distinct antigenic epitopes have been identified on DIII of the E protein.
One of them, the lateral ridge epitope, is targeted by antibodies that have demonstrated
protective efficacy in vivo, while the other two epitopes elicit poorly- or non-neutralizing
antibodies. Our goal is to engineer antigens that elicit ZIKV-neutralizing antibodies and
minimize the generation of antibodies that don’t confer protection against the virus. Our
approach involves the design of recombinant antigenic proteins incorporating unnatural
amino acids and site-specific protein functionalization with polyethylene glycol (PEG)
groups. This will allow us to shield with PEG the two epitopes that do not elicit neutralizing
Zika antibodies, leaving exposed only the lateral ridge epitope. This will be followed by
multivalent attachment of these modified proteins to scaffolds in order to enhance B cell
activation. Immunization with this engineered antigen should result in a higher generation
of neutralizing antibodies towards the lateral ridge epitope. Preliminary ELISA results
demonstrate our ability to focus antibody binding on targeted DIII epitopes while shielding
non-neutralizing epitopes. We are currently finalizing in vivo studies and will next confirm
the ability to focus the immune response on ZIKV-neutralizing epitopes and to protect mice
from a ZIKV challenge.
25. Structural Characterization of a Drug Carrier for Intracellular
Antibody Delivery
Anshul Dhankher / Prof. Julie A. Champion
In recent years, antibodies have shown great promise as therapies in multiple disease areas.
However, the application of antibodies is restricted to a small number of extracellular therapeutic targets since they can’t cross the cell membrane. To target intracellular
proteins, we developed a self-assembling protein carrier that binds the constant region (Fc)
of antibodies and delivers them intracellularly. The carrier is comprised of a self-assembling hexamer barrel (Hex) with an Fc binding domain fused to each monomer of
the barrel. Further application of the drug carrier requires characterization of the Hex
antibody complexes. In order to understand the maximum antibody loading capacity of Hex carriers, mixtures of Hex-IgG (Immunoglobulin G, a non-specific antibody) at various
Hex to IgG ratios were analyzed by size exclusion chromatography in tandem with multi
angle light scattering. We found that a 1 to 3 molar ratio saturated Hex carriers but yielded two separate populations, one at the expected molecular weight of 1 Hex to 3 IgG, and
another much larger. In addition, stability studies of the Hex-IgG complexes with dynamic
light scattering showed a decrease in particle size over time, which was accelerated by incubation at higher temperatures. Further characterization demonstrated that the larger
molecular weight species had largely disappeared into the expected 1:3 molecular weight, indicating rearrangement of the Hex-IgG complexes into a 1:3 ratio. Preliminary results
15
demonstrated that aging of the Hex-IgG complexes can improve the intracellular delivery
of antibodies, relating the structural rearrangement to a functional improvement. 26. Non-enzymatic nucleic acid ligation: Rules for using carbodiimides
Chiamaka Obianyor / Prof. Martha Grover
RNA is often considered a major precursor to cellular life. However, a prebiotic mechanism
that permits multiple rounds of RNA replication has not been discovered. The discovery of
a pathway to non-enzymatic replication is often hindered by the inability to ligate
mono/oligo-nucleotides without the use of enzymes. Several pathways have been proposed
previously to solve this problem, including the use of activated primers to enable ligation
of mononucleotides, and the formation of new RNA strands from transesterification
reactions. Nevertheless, the lack of a simple pathway for the prebiotic production of these
activated primers, and low yield from transesterification reactions have prevented the
advancement of these ideas. The goal of this research is to elucidate common principles
that could explain the low yields often encountered in non-enzymatic ligation and guide
the development of future ligating systems. Using carbodiimides as the activating agent for
the formation of a phosphodiester bond, we demonstrate the feasibility of RNA as a
potential prebiotic biopolymer. We observe that the hybridization of the oligonucleotides
to the template is the rate limiting step of non-enzymatic template directed ligation
reactions. Additionally, we found that the pre-alignment of the cyclic phosphate
intermediate for RNA ligation determines the formation of products, thus explaining why
transesterification reactions only occur efficiently in naturally evolved systems.
Altogether, our results demonstrate how different factors could have played a role in the
earliest RNA ligation systems and the relevance of these factors in determining the first
prebiotic biopolymer.
27. Novel Supply Chain and Process Modeling for Cell Therapy
Manufacturing
Yi Liu / Prof. Chip White
Cell therapy is a rapidly growing industry with its unique production and supply chain
complications. We present a two-level hierarchical supply chain model of autologous
CAR-T cell therapy that serves as the basis for the development of strategies to: 1) deliver
cell therapy products that are safe and have a high level of efficacy, 2) minimize fulfillment
time and variability, and 3) reduce total manufacturing and logistics costs while reducing
the risk of patient morbidity and mortality. The model consists of two integral components:
(1) an agent-based program for a “single manufacturing facility” that simulates the
manufacturing and quality control process of cell therapy; and (2) a supply chain network
program that evaluates different supply chain configurations and sourcing strategies. The
two-level hierarchical supply chain model can be used as a decision support system to
explore manufacturing, quality assurance, and supply chain and logistics ‘what if’
questions. Using the model, we explored the impact of reagent supply chain disruptions to
manufacturing and evaluated the effectiveness of different tools that can mitigate
unexpected supply disruptions. We intend to use this model to support the design and
operation of supply chains for end-to-end manufacturing and logistics of large-scale, low-
cost, reproducible and high-quality cell therapy products.
16
Oral Presentation Session I
Materials and Nanotechnology
Ion-sieving carbon nanoshells for deeply rechargeable Zn-based aqueous
batteries
Yutong Wu /Prof. Nian Liu
As an alternative to lithium-ion batteries, Zn-based aqueous batteries feature non-
flammable electrolyte, high theoretical energy density, and abundant materials. However,
a deeply rechargeable Zn anode in lean electrolyte configuration is still lacking. Different
from the solid-to-solid reaction mechanism in lithium-ion batteries, Zn anodes in alkaline
electrolyte go through a solid-solute-solid mechanism (Zn-Zn(OH)42--ZnO), which
introduces two problems. First, discharge product ZnO on the surface prevents further
reaction of Zn underneath, which leads to low utilization of active material and poor
rechargeability. Second, soluble intermediate changes Zn anode morphology over cycling.
In this work, we report an ion-sieving carbon nanoshell coated ZnO nanoparticle anode,
synthesized in a scalable way with controllable shell thickness, to solve the problems of
passivation and dissolution simultaneously. The nano-sized ZnO prevents passivation,
while microporous carbon shell slows down Zn species dissolution. Under extremely harsh
testing conditions (closed cell, lean electrolyte, no ZnO saturation), this Zn anode shows
significantly improved performance than Zn foil and bare ZnO nanoparticles. The deeply
rechargeable Zn anode reported is an important step towards practical high-energy
rechargeable aqueous batteries (e.g. Zn-air batteries). And the ion-sieving nanoshell
concept demonstrated is potentially beneficial to other electrodes such as sulfur cathode
for Li-S batteries.
The Geode Process: A Route to the Large-Scale Manufacturing of
Functionally-Encoded Semiconductor Nanowires Maritza Mujica / Prof. Michael Filler
Future large-area electronic and photonic technologies will require the manufacturing of
materials and devices at very high rates without sacrificing nanoscale control of structure
and composition. Semiconductor nanowires can be produced with exquisite spatial control
of composition and morphology using the vapor-liquid-solid (VLS) mechanism that,
unfortunately, remains limited to very small manufacturing rates. Here, we introduce the
Geode process to synthesize functionally-encoded semiconductor nanowires at
throughputs orders of magnitude beyond the state-of-the art. Central to the Geode process
are sacrificial, porous-walled, seed particle-lined silica microcapsules, whose interior
surface serves as a high-surface area growth substrate. Microcapsules protect the growing
nanostructures, are produced with a scalable emulsion templating technique, and are
compatible with large-scale chemical reactors. We will show how microcapsule structure
and drying is influenced by silica nanoparticle type and concentration, emulsification
parameters, and nanoparticle cross-linking agent. We will also demonstrate the synthesis
of Si nanowires with programmable dopant profiles on the microcapsule interior, which
not only shows the versatility of the process, but also allows the impact of precursor gas
transport limitations to be characterized.
17
Control of Nucleation Density in Conjugated Polymers via Seed
Crystallization
Michael McBride/ Prof. Martha A. Grover
Desired semiconducting electronic properties of conjugated polymer systems are highly
dependent on the thin film morphology. The requirement of interconnected assemblies has
been deemed most influential for long range percolative charge transport. However, entanglement effects in conjugated polymers severely limits the π stacking of polymer
chains into interconnected crystalline domains. The entanglement of individual chains can
be reduced through solution processing methods that promote the nucleation and growth of tightly packed, ordered structures.
Herein, we demonstrate facile solution processing methods to target the formation of
interconnected assemblies. Poly(3-hexylthiophene) (P3HT), the canonical semicrystalline
conjugated polymer to investigate the mechanism of self-assembly in solution, was utilized
as a representative model polymer. Manipulation of the polymer molecular weight
distribution, solute-solvent interactions via solution environment, and quantity of seed
nuclei are shown to be tunable parameters impacting the degree of interconnectivity during
self-assembly. Both the generality and limitations of these approaches were investigated
using a wide array of nucleation events including exposure to low dose UV, microfluidic
flow processing, and poor solvent addition. A particularly promising approach involves the
selective mixing of a nucleated polymer solution with a non-nucleated sample.
Mechanistically, highly crystalline and order domains can be formed during primary
nucleation and then interconnected via secondary nucleation. These processing approaches
have improved the charge carrier mobility from a base of ~10-3 to exceeding 0.200 cm2/V-
s. General process-structure-property relationships were developed to quantitatively
describe the tradeoffs between polymer network formation and grain boundaries on charge
transport. All examined cases suggest an optimal processing window for long range
interconnectivity.
Rheological Characterization of Nanocellulose Materials for Quality
Control
Jianshan Liao/ Prof. Victor Breedveld
Nanocellulose material is a renewable and sustainable nanomaterial produced from
abundant cellulose sources. Its high strength and biodegradability make it attractive to
many applications such as composites, coatings and rheological modifiers. To ensure
consistent production of high quality nanocellulose materials, one of the most urgent issues
to be addressed is the lack of standardized, rapid and reliable characterization methods.
Current techniques, such as electron microscopy and light scattering, are expensive and
time-consuming. Moreover, they only probe a small portion of the nanocellulose sample,
which may misrepresent the sample’s bulk properties. Rheology provides a fast and cost-
effective way to characterize nanocelluloses in large volume. In this work, we will show
the influence of concentration and salt content on rheological properties of cellulose
nanocrystal and TEMPO oxidized cellulose nanofiber. A rheological model was
formulated to capture the viscosity across shear rates and concentrations. We will also
demonstrate the change of fiber length and carboxylic content of cellulose nanofiber
reflected on the change of their rheological properties, which can be captured by the
rheological model.
18
Oral Presentation Session II
Materials and Nanotechnology
Vapor Phase Infiltration of Metal Oxides into Microporous Polymers for
Solvent Stable Nanofiltration Membranes
Fengyi Zhang / Prof. Ryan P. Lively
Owing to their high surface area and hierarchical porosity, microporous polymers, such as
polymers of intrinsic microporosity (PIMs), have shown great potential in heterogeneous
catalysis, adsorption, and membrane separations, among other applications. Linear
microporous polymers (e.g., solution-processable PIM-1), can be easily manufactured into
form factors consistent with large-scale separations (e.g., hollow fibers). However, the
limited organic solvent resistance of linear microporous polymers restrict their application
in aggressive operating environments. Two of the most prominent post-fabrication
methods for improving the stability of polymers are pyrolytic carbonization and
crosslinking. These are both promising approaches to rigidifying polymeric materials, but
require a near-complete transformation of the precursor in the former case and
chemical/thermal treatments in the latter case.
Here, we develop a novel post-fabrication modification technique for improving the
stability of microporous polymers without damaging the microstructure and macroscale
form factors. Cyclic vapor phase infiltration of metal-organic precursors and water into the
structure of PIM-1 creates monolayers or bilayers of sub-nanometer metal oxide structures
on the surfaces of the interconnected PIM-1 micropores. The resulting interpenetrating
atomic-scale networks of metal oxide and PIM-1 retain the microporosity and exhibit
excellent solvent resistance to strong solvents for PIM-1 (chloroform, dichloromethane,
and tetrahydrofuran). While PIM-1 membranes cannot effectively reject polystyrene
oligomers below 1200 g/mol from ethanol, the hybrid PIM-1 membranes reject polystyrene
oligomers larger than 400 g/mol. Besides, the interpenetrating aluminum oxide networks
inhibit the interaction between membranes and solutes, increasing the Rose Bengal
rejection from 45% to 86%. Since the vapor phase infiltration process can be directly
applied to state-of-art membrane modules, this treatment has the potential to be adopted
into the large-scale manufacturing of advanced membranes.
Evidence for entropic diffusion selection of xylene isomers in polymer
derived carbon molecular sieve membranes
Yao Ma / Prof. Ryan P. Lively
The purification of benzene derivatives, particularly xylene isomers, is one of the most
important organic mixture separations practiced in industry. The separation of xylene
isomers is especially challenging due to the similarity of their physical properties. Carbon
molecular sieve (CMS) membranes are promising materials for such challenging solvent
separations due to their thermal and chemical stability, but these materials have not been
studied in detail in the case of large organic molecules. Xylene isomer transport and
sorption properties in a CMS membrane derived from a prototypical polymer of intrinsic
microporosity (PIM-1) reveal that diffusion selectivity is the dominant factor in
contributing to the preferential permeation of p-xylene over o-xylene. Moreover, the
contributions of “enthalpic” and “entropic” selectivity to the diffusion selectivity are
studied in detail and reveal that entropic factors dominate the xylene selection mechanism.
Overall, this study provides fundamental insight and guidance into the separation of large
organic molecules in amorphous microporous materials.
19
Synthesis and Properties of Degradable Polyaldehyde Copolymers
Anthony Engler / Prof. Paul Kohl
Polyaldehydes are metastable materials at ambient conditions due to their typically low
thermodynamic ceiling temperature (TC), or the equilibrium temperature between
monomer and polymer. Breaking one backbone bond in the polymer above the TC will
initiate total depolymerization down the polymer chain, converting back to aldehyde
monomer. Polyaldehydes have yet to find a robust application in materials, because of their
instabilities at ambient temperatures. Rather than a drawback, the low TC phenomenon
offers a unique advantage in the degradation of polymers due to the minimum activation
energy required to degrade an entire polymer chain. This ability to rapidly convert to small
molecules makes polyaldehydes well suited for applications in stimuli-responsive
materials, transient technology, and sacrificial materials. Novel copolymers were
synthesized using a variety of aliphatic and functional aldehydes with o-phthalaldehyde,
which provides high molecular weight and stability. Reactivity behavior of aliphatic
aldehydes correlates positively with the aldehyde’s hydration equilibrium constant (KH),
with electron-deficient aldehydes incorporating into copolymers at higher percentages.
Higher incorporations of aliphatic aldehydes bring about lower molecular weight
polymers. The polymerization is tolerant to chain length, branching, non-conjugated
unsaturation, halogens, and sulfonate esters. Post-polymerization modifications are
performed to introduce inaccessible functional groups like epoxy, thioethers and azides.
Applications towards transient technology are discussed.
Facile Integration of Porous Nanomaterials on and from Support Media
Jayraj N. Joshi / Prof. Krista Walton
Unconventional strategies for synthesizing advanced separation materials can reduce
manufacturing complexity while affording economic and environmental benefits.
Accordingly, we present a novel method for producing supported porous nanomaterials
both from and on aluminum-based support structures. Supported MOF composites are
created in one-step from inexpensive aluminum oxides, alloys, meshes, foil, and even
recycled beverage cans. Microscopy reveals uniform monolayer epitaxial MOF growth.
The same strategy is adapted to different framework systems, as well as non-supported
adsorbent production with unique textural properties. Scaffolded microneedle MIL-53(Al)
MOFs produced from this study are additionally ideal precursors for creating supported
aluminum oxide nanotubes. Through MOF pyrolysis, micro/mesoporous alumina
structures emerge 1-5µm perpendicular from the underlying support. In addition to the
conventional uses of alumina as catalyst and adsorbent supports, newly-generated oxides
investigated here afford unique MOF regrowth and acid gas remediation applications.
Presented findings establish a simple and accessible gateway for building nanoscale-
controlled devices, hierarchical separation media, and high performance membranes.
20
Comprehensive Study of SO2 Adsorption in a Series of Metal-organic
Frameworks
Julian Hungerford / Prof. Krista Walton
A series of Metal-organic Frameworks (MOFs) were synthesized and SO2 adsorption
isotherms were collected on a lab build pressure decay apparatus to develop structure-
property relationships. The MOFs tested included: DMOF-TM, DMOF-ADC, MIL-
53(Al), Cu-BTC, UiO-66, MIL-101(Cr), ZIF-7, ZIF-8, ZIF-11, and ZIF-65. All MOFs
used in this study were found to be stable upon exposure to SO2 for the duration of the
isotherm collection. We established that MOFs with larger pore volumes correlated with
higher SO2 adsorption capacity at high SO2 pressure. MIL-101(Cr) had the highest SO2
adsorption capacity of 21 mmol/g while also having the largest pore volume of 1.3 cm3/g.
MIL-53(Al), Cu-BTC, and ZIF-65 displayed similar SO2 adsorption capacities of roughly
12 mmol/g while having similar pore volumes. ZIF-7 and ZIF-11 adsorbed very little SO2
at all adsorption points, these materials have pore diameters smaller than the kinetic
diameter of SO2 and we hypothesize that any SO2 adsorption is likely due to structure
defects or linker flexibility. When analyzing the low pressure region of the SO2 adsorption
isotherms for these MOFs a different relationship is observed. Cu-BTC, a MOF containing
open metal sites (OMS), displayed strong SO2 adsorption at the lowest adsorption points.
DMOF-TM does not contain OMS, however it displayed greater low pressure adsorption
than Cu-BTC. The pore diameter of DMOF-TM is nearly identical to the kinetic diameter
of SO2 such that molecular sieving may contribute to a large SO2 adsorption at low
pressure. Our overall findings show that MOFs with the large pore volumes will have large
SO2 adsorption capacities at high pressures, while OMS or molecular sieving dominate the
low pressure region.
21
Selective CoAxial Lithography via Etching of Semiconductors (SCALES):
A Bottom-up Nanoscale Patterning Process for Very Large-Scale Electronic
Device Manufacturing
Amar Mohabir / Prof. Michael Filler
Nanoscale electronic devices, such as field effect transistors, contain one or more features
with nanoscale dimensions. When such devices are to be produced at very large
manufacturing rates (e.g., for large-area integrated circuitry), a bottom-up alternative to
top-down patterning is necessary to define these features. Here, we show how surfaces with
regions of differing composition can be selectively masked using surface-initiated growth
of polymer films. Our approach is particularly useful for patterning semiconductor
nanowires where composition is modulated along the nanowire length. Surface masking is
accomplished in a two-step procedure. (1) Atom transfer radical polymerization (ATRP)
of polymethylmethacrylate (PMMA) first occurs from a surface-tethered initiator in a
blanket fashion, covering all surfaces regardless of composition. (2) A subsequent selective
etch removes the polymer only from regions whose underlying surface is susceptible to the
etchant. We apply this technique, dubbed Selective CoAxial Lithography via Etching of
Semiconductors (SCALES), to nanowires containing axially-modulated doped/undoped Si
and Si/Ge regions. For the case of doped/undoped Si nanowires, KOH removes PMMA
from the undoped regions but does not attack the doped regions. For the case of Si/Ge
nanowires, PMMA is removed from the Ge regions by etching with H2O2 but remains on
the Si regions. We investigate the role of surface pre-treatment, PMMA polymerization
parameters, and post-polymerization etching on the SCALES process with a suite of
spectroscopy and microscopy techniques. The ability to mask nanoscale objects in a
bottom-up fashion opens up the possibility of nanoscale patterning in a truly scalable
manner.
A Database of 2D Zeolite Nanosheets: Development and Applications
Omar Knio / Prof. David S. Sholl
Zeolites are nanoporous aluminosilicates widely used in catalysis and separations
applications. Though generally formed as 3D crystals, new synthesis techniques have given
access to 2D zeolite nanosheets with small diffusion path lengths and accelerated molecular
diffusion. Since most previous research has focused on bulk zeolite crystals, there is little
understanding of the surface adsorption and diffusion mechanisms likely involved at such
length scales and their contributions to the permeability and selectivity of different species.
To enable the systematic examination of such surface properties, we constructed a database
of more than 800,000 computation-ready 2D zeolite nanosheets from the full range of
known zeolite structures in the IZA database of zeolite structure types. The nanosheet
surfaces cover a wide range of orientations and were created via the principle of minimizing
the number of bonds broken during the termination of a unit cell. The database consists of
two sets of nanosheets: one set with known heights and unrelaxed surfaces, and another set
with arbitrary heights and relaxed surfaces.
22
As an initial example of the utility of this database, we generated equilibrium Wulff shapes
for 203 3D zeolite structure types in the International Zeolite Association (IZA) database.
Since our database is pure silica, our predicted crystal shapes resembled experimentally
synthesized crystals with high Si:Al ratios. Finally, we used Molecular Dynamics to
identify zeolite nanosheet properties ideal for the industrially relevant separation of H2
from CO2. To that end, we examined the surface contribution to diffusion as a function of
slab height in MFI, a widely used zeolite. By incorporating surface effects, the current
study lays the groundwork for high throughput screening of zeolite nanomaterials in their
thinnest and most promising form.
Oral Presentation Session III
Energy and Sustainability Ethylene/Ethane Separation in Metal-Organic Frameworks by
Computational Modeling
Wenqin You / Prof. David S. Sholl
Metal-organic frameworks (MOFs) with open metal sites (OMS) are known to be selective
for ethylene relative to ethane. In practical applications of this separation, the presence of
other small molecules such as H2O, CO, and C2H2 may affect the suitability of sorbents.
We used density functional theory (DFT) calculations to compute the binding energies of
H2O, CO, C2H2, C2H4, and C2H6 in M-BTC (BTC = 1,3,5-benzenetricarboxylic acid) with
12 different metals forming OMS (M = Mg, Ti, V, Cr, Mo, Mn, Fe, Ru, Co, Ni, Cu, and
Zn). To probe the generality of these results for MOFs containing other ligands, we
performed similar calculations for metal-substituted MOFs based on four more materials
with dimeric Cu sites. Our results provide useful insights into the variations in binding
energies that are achievable by metal substitution in this broad class of MOFs, as well as
pointing towards feasible adsorption-based separation strategies for complex molecular
mixtures. Zn OMS MOFs were predicted to have the highest C2H4/C2H6 selectivity, but the
strong binding energy of solvents and other small molecules in these materials may create
practical challenges. We used DFT calculations to examine whether functionalizing linkers
in these materials with electron withdrawing (-fluorine) and donating (-methyl) groups
offer a useful way to tune molecular binding energies on OMS in these materials.
Zinc anode design for rechargeable aqueous high-energy Zn-air batteries
Yamin Zhang / Prof. Nian Liu
As an energy storage system, Li-ion batteries are not safe because they use flammable
organic electrolytes. A safer alternative is rechargeable Zn-based batteries with aqueous
electrolytes. Among them, Zn-air batteries have high theoretical volumetric energy density
(4400 Wh/L), which can even compete with lithium-sulfur batteries. Alkaline electrolyte
is preferable for Zn-air batteries. However, the performance of Zn anodes in alkaline
electrolyte is limited by passivation, dissolution and hydrogen evolution. Through SEM
investigation, critical passivation size was found to be ~ 2 µm. Sub-micron-sized Zn anodes
won’t have passivation problem. As a result, we focus our research on nanoscale. However,
Zn dissolution of nanosized anodes will be accelerated because of large electrode-
electrolyte surface area.
Thus, anode modification and protection are needed to alleviate the dissolution. We
designed a (1) Zn mesh@GO anode: GO layers on the Zn mesh surface deliver electrons
across insulating ZnO and can slow down the Zn dissolution; (2) lasagna-inspired
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ZnO@GO anode: ZnO nanoparticles encapsulated by GO can solve simultaneously the
passivation and dissolution problems; (3) core-shell ZnO@TiN nanorod anode: thin and
conformal TiN coating mitigates Zn dissolution, mechanically maintains the nanostructure,
and delivers electron to nanorods.
Hydrogen evolution is a competitive side reaction on the zinc anodes, which causes low
efficiency of Zn based batteries. Our approach is to suppress hydrogen evolution by
modifying the anode with a hydrogen suppressive material: core-shell ZnO@TiO2 nanorod
anode was made with hydrogen suppressive TiO2 coating, which solves hydrogen
evolution, passivation and dissolution problems at the same time.
All of these anodes show superior performance compared with unmodified anodes. These
anodes can be paired with air cathodes to make high energy Zn-air batteries. The nanoscale
design principles here can potentially be applied to overcome intrinsic limitations of other battery materials.
Continuous Zeolite MFI Membranes Fabricated from 2D MFI Nanosheets
on Ceramic Hollow Fibers Byunghyun Min / Prof. Sankar Nair
This work addresses the challenge of fabrication of 2D MFI hollow fiber membranes.
Defect-free 2D MFI nanosheets coating is prepared on the α-alumina hollow fiber support
by simple vacuum filtration method. Then, it is intergrown into a continuous film after
TPA-F hydrothermal treatment by sealing the gaps and increase the adhesion of the
membrane on the support without need of any support modification. Sequential TEAOH
hydrothermal treatment improves the intergrowth by selectively reducing small defect area
further. Sequential steps are optimized to selectively seal the gaps while minimizing the
overgrowth and twinning to preserve the preferred b-out-of-plane orientation and thin
thickness. This microstructurally optimized 2D MFI membrane supported on hollow fiber
exhibits high-performance for separation of n-butane from i-butane. These findings will
provide the implications for scale-up of the 2D MFI membrane with enhanced separation
performances for industrially important molecules.
Selective Removal of Hydrogen Sulfide from Biogas Streams Using
Sterically Hindered Amine Adsorbents
Claudia N. Okonkwo / Prof. Christopher W. Jones
Sterically hindered amines in solution have been explored for H2S capture and they have
been found to be selective for removing H2S over CO2 compared to the conventional
methyl diethanolamine (MDEA) or unhindered amines. A disadvantage with these amine
solutions is the high regeneration energies required while operating practical, aqueous
systems. As a result, the use of solid supported materials with lower heat capacities and
improved energy costs has been proposed. This work uses sterically hindered amines on
solid supported materials to determine their H2S selectivity in the presence of CO2 and
CH4. Using a breakthrough apparatus, in-situ infrared spectroscopy and thermogravimetric
analysis we have investigated (i) the H2S selectivity in a multicomponent gas mixtures, (ii)
the nature of the chemisorbed species formed during H2S adsorption and (iii) the effect of
concentration and temperature on H2S adsorption performance on these sterically hindered
amine adsorbents under dry conditions.
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Oral Presentation Session IV
Energy and Sustainability Kinetics of CO2 adsorption in amine-functionalized materials with stepped
isotherms Trisha Sen / Prof. Matthew J. Realff
CO2 uptake in amine-functionalized MOFs, such as Mg2(dobpdc), follows a tunable
stepped isotherm behavior, which enables unprecedented high equilibrium and pressure-
swing capacities for CO2 capture under DAC (Direct Air Capture) conditions (< 0.4 mbar).
This study attempts to move beyond the equilibrium understanding of these materials, by
analyzing their kinetics associated with DAC and to determine whether this limits their
practical application.
An adsorption breakthrough setup with ultra-dilute (0.4 mbar) and dilute (1 mbar, 5 mbar
and 10 mbar) feed was used as a proxy to simulate practical systems. Local equilibrium
theory for stepped isotherms predicts a simple single shock breakthrough for CO2
concentrations above 1% (or 10 mbar). Below 10 mbar, we expect two shocks separated
by a plateau corresponding to the isotherm step pressure. The predicted shapes of the
breakthrough profiles matched the experimentally observed results only qualitatively.
Attempts to fit a traditional LDF mass transfer model to match the observed data were
unsuccessful. While CO2 is simply physisorbed below the isotherm step, a cooperative
mechanism kicks in once this critical loading has been achieved. To capture these kinetics,
a simple LDF model before the isotherm step change and a model for co-operative uptake
(Avrami / Michaelis-Menten) above the step were implemented. Further, quantifying the
CO2 capture fraction of the bed at saturation showed that the bed utilization efficiency is
severely reduced at low feed concentration especially with increasing flowrates.
The aim of this work is therefore two-fold. Firstly, to understand and quantify the system
kinetics of amine functionalized adsorbents with stepped isotherms. Secondly, this study
indicates that moving beyond equilibrium or swing capacity of these adsorbents, and
looking at their kinetics is crucial to assess their efficiency in practical DAC applications.
Complex Systems Impurity control in the continuous reactive crystallization of beta-lactam
antibiotics Matthew A. McDonald / Prof. Martha A. Grover Beta-lactam antibiotics such as cephalexin and ampicillin can be synthesized and
crystallized simultaneously with the use of penicillin G acylase (PGA) as a catalyst.
However, PGA also catalyzes the degradation of the antibiotic to form a slightly soluble by-product—phenylglycine in the case of cephalexin or ampicillin—that can contaminate
the solid product [1]. It is important that by-product concentration remain below the
solubility limit so that pure antibiotic can be filtered immediately without the need for recrystallization or other further purification. In a continuous process, online detection of
phenylglycine crystals is necessary to ensure product quality. Focused beam reflectance
measurement (FBRM) has been used to observe the nucleation of the byproduct in real
time. However, it is desirable to take preemptive action to avoid nucleation of the by-
product at all. The combination of several process analytical technologies such as ATR-
FTIR and inline polarimetry enable the detection of phenylglycine before the solubility limit is reached. Purity can then be enforced by changing the crystallizer conditions to
increase enzyme selectivity or decrease enzyme activity, both at a cost to productivity and
conversion, but without the need to stop the continuous process due to solid phase impurity. A model of the reactive crystallization system is used to inform controller actions.
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Experiments conducted in a fed-batch crystallizer, where phenylglycine accumulation is
easier to control, are used to evaluate phenylglycine crystal detection by FBRM as well as
model accuracy. A mixed-suspension mixed-product removal (MSMPR) crystallizer is
used to evaluate different control actions, such as decreasing pH (which simultaneously decreases antibiotic solubility and increases PGA selectivity), changing temperature
(increasing temperature decreases solubility of phenylglycine but increases PGA activity
while decreasing temperature has the opposite effect), and changing feed reactant concentrations (changing the reactant ratio affects both selectivity and activity).
[1] McDonald, M.A., Bommarius, A.S., and Rousseau, R.W. (2017) Chem. Eng. Sci. 165,
81-88.
Biotechnology Serum effects on nanoparticle-mediated photoporation for enhanced
macromolecular delivery
Simple Kumar / Prof. Mark R. Prausnitz
Intracellular delivery of therapeutic and diagnostic molecules is restricted by plasma
membrane. Often, endocytic route is used to transport molecules inside cells, which can
render these molecules inactive due to pH changes. Nanoparticle-mediated photoporation
offers a physical route to create transient pores allowing uptake of foreign molecules by
cells. Through near-infrared laser irradiation, nanoparticles absorb and dissipate energy to
the surroundings, vaporizing water to create steam bubble. The subsequent thermal and
acoustic outputs are believed to be responsible for membrane poration. This process has
been optimized for >90% cellular uptake of low-molecular weight molecules without
significant cell viability loss.[1] Comprehending how changes in cellular micro-
environment affect delivery efficiency is important for clinical translation of this platform
technology. Therefore, this study is focused on understanding the role of serum during
photoporation.
Experimental results reveal 75% less loss of cell viability during laser irradiation at high
fluence when cells are suspended in media containing 10 (v/v)% serum. Similar effects are
observed in media containing denatured serum. Further experiments show that some
polymer additives also help preserve cell viability and thus viability protection by serum
appears to be attributed to physical property changes in suspension media and not to
biological activity introduced by serum proteins. Thus far, nanoparticle-mediated
photoporation has been used to efficiently deliver molecules below 15 kDa range. Larger
size molecules may require high fluence which often leads to cell viability loss. However,
using serum’s viability preservation at high fluence, we were able to deliver 40 kDa, 150
kDa and 500 kDa dextran to >50% cells in presence of serum. Further optimization can
allow us to deliver these macromolecules with higher efficiencies.
[1] Sengupta et al. Efficient Intracellular Delivery of Molecules with High Cell Viability
Using Nanosecond-Pulsed Laser- Activated Carbon Nanoparticles. ACS Nano 2889–2899
(2014)
Novel Supply Chain and Process Modeling for Cell Therapy Manufacturing
Yi Liu / Prof. Chip White
Cell therapy is a rapidly growing industry with its unique production and supply chain
complications. We present a two-level hierarchical supply chain model of autologous
CAR-T cell therapy that serves as the basis for the development of strategies to: 1) deliver
cell therapy products that are safe and have a high level of efficacy, 2) minimize fulfillment
time and variability, and 3) reduce total manufacturing and logistics costs while reducing
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the risk of patient morbidity and mortality. The model consists of two integral components:
(1) an agent-based program for a “single manufacturing facility” that simulates the
manufacturing and quality control process of cell therapy; and (2) a supply chain network
program that evaluates different supply chain configurations and sourcing strategies. The
two-level hierarchical supply chain model can be used as a decision support system to
explore manufacturing, quality assurance, and supply chain and logistics ‘what if’
questions. Using the model, we explored the impact of reagent supply chain disruptions to
manufacturing and evaluated the effectiveness of different tools that can mitigate
unexpected supply disruptions. We intend to use this model to support the design and
operation of supply chains for end-to-end manufacturing and logistics of large-scale, low-
cost, reproducible and high-quality cell therapy products.
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Acknowledgements
2019 Graduate Symposium Executive Boards
Chairs
Juan Luis Mena Lapaix Samantha Pustulka Vice Chairs
William Bradley Rohan Murty Hospitality
Maggie Manspeaker Maritza Mujica Zhenzi Yu Media
Youn Ji Min Geetanjali Pendyala Young Hee Yoon Abstract
Qandeel Almas Hye Youn Jang Rebecca Schneider Food
Chunyi (Alexis) Li Sang Jae Park Brianna Thornton Logistics
Jane Agwaro Andrew Kristoff Matthew Warner
Special Thanks to:
Faculty Speakers
Dr. Christopher Jones Dr. David Sholl
Event Coordinators
Ms. Donna Peyton Dr. Sankar Nair
Poster Session Judges
All ChBE Faculty Volunteers
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Sponsors