Facility for Light Scattering: Current Projects

Sara M. Hashmi, Ph.D., Director Department of Chemical & Environmental Engineering

December 11, 2015

786

LightScattering.Yale.edu

Structure Function

Dynamics

Bridging the Gap…

Microscale

Macroscale

aggregation

diffusion

Facility for Light Scattering NanoBrook Omni

Brookhaven Instruments: DLS, Zeta Potential, PZC

Mason B7

ALV 5000 goniometer ALV-GmbH:

DLS, MALS, SLS Dunham 124c

Instrumentation

Measurement Concepts: DLS

Laser

Scattering Angle:

nm

Detector

Dynamic Light Scattering: Assessing Diffusion in Suspension

10ï3 100 1030

0.2

0.4

0.6

0.8

1

6t (ms)

g(6

t)Collected scattered light intensity fluctuates due to diffusion in the sample

g(Δt) ≈ exp(−Δt τ )

τ

Diffusive time scale

λ = 532

How does LS work?

θ = 900

106 107 10810ï1

100

101

q (1/nm)

o (s

)

protein 1combination

Measurement Concepts: MALS •  Multiple Angle LS •  Dynamics at all angles

Suspension

Detector Array

Laser

q = 4πnsin θ 2( ) λ

nm λ = 532

Units = [1/L]

Diffusion = Length2

Time

10ï3 100 1030

0.2

0.4

0.6

0.8

1

6t (ms)

g(6

t) τ

At each angle: diffusive time

scale

How does LS work?

106 107 10810ï1

100

101

q (1/nm)

o (s

)

protein 1combination

-2 Sub-diffusive

motion on shortest

length scales

Regan Lab

Measurement Concepts: SLS •  Static Light Scattering: measure profile I(q) •  Analog of XRD

Suspension

Detector Array

Laser

q = 4πnsin θ 2( ) λ

nm λ = 532

Units = [1/L]

How does LS work?

10-2

1x10-5

1x10-4

10-3

8 h

10 h

13 h

28 h

31 h

I / I 0

q [nm-1]

0,029 0,030 0,031

1x10-5

10 h

31 h

I / I

0

q [nm-1]

Example: precipitating metal oxide NPs

fDqI −≈

-2

Isotropic scattering from <20nm particles Profile scales as when size à 1/q

aQeπη

µ6

≈Balance electrostatic and hydrodynamic forces:

+ -

Ev

≡µ

v

Zeta Potential is measured via Phase Analysis Light Scattering (PALS) Analogous to Doppler shift, with oscillating electric field

with electric field E: diffusion with drift Measurement Concept: Zeta Potential

Electrophoretic mobility:

Drift velocity:

How does LS work?

Diffusive trajectory

Initial position

Final position

Understanding Dynamics •  Particle size distributions and morphology •  Precipitation processes, gel growth •  Aggregation (often driven by electrostatics) •  Sedimentation (or creaming)

Dynamics Reveals Mechanisms & Interactions

Ca2+

Ca2+ Ca2+

Ca2+

Ca2+

Ca+2 Ca+2

Ca2+

Ca2+

Ca2+

Ca2+

Ca2+ Ca2+

Ca2+ Ca2+

Ca2+ >>Ass.

Dis.<<

>>Ann.

Fra.<<

Marine Hydrogels

What do we measure?

TEM: Dark blue precipitate

Materials Characterization

•  Nanotubes & Nanowires •  NPs (metal oxides, polymers) •  Liposomes & micelles •  Emulsions, gels, & proteins

Structure Determines Function

What do we measure?

Nano-hematite, iron oxide

Application: Emulsion Filtration

Jongho Lee, Chanhee Boo, Meny Elimelech (preliminary results).

Mineral oil in water, 0.01g/mL, with Tween 80

102 1030

0.02

0.04

0.06

0.08

0.1

a (nm)

p(a)

102 1030

0.02

0.04

0.06

0.08

0.1

a (nm)

p(a)

Project Examples

Before Filtration

After Filtration

GOAL: Enhance water permeability and reduce oil fouling through super-hydrophobic/omniphobic membranes

Cellulose Nanofibers Triton X-100 micelles facilitate CNF bridging

Application: Rheological Modification

Neat TX100 5%

Neat CNF 0.1%

(a)

(b)

(c)

Quennouz, Hashmi, Choi, Kim, Osuji. Soft Matter Advance Article (2016).

Neat CNF 0.5

1 2 5

TX100

Project Examples

Appearance of 2 time scales indicates internal structure

102 1040

0.5

1

1.5

x 10ï3

o (µs)

p (o

)

Structure ßà Function CNT Dispersion Quality Determines Cytotoxicity

…also Absorption, Reactivity

Loss of Bacterial Cell Viability for Nine fSWNTs

n-Prop

ylamine

Phenylh

ydraz

ine

Hydrox

y

Phenyld

icarbo

xyPhen

yl

Sulfon

ic Acid

Startin

g Mate

rial

n-Buty

l

Dipheny

lcyclo

propan

e

Hydraz

ine50

60

70

80

90

100

Surface Functional Group

Loss

of C

ell V

iabili

ty (%

) * * * **

*

* *102 1040

0.5

1

1.5

x 10ï3

o (µs)

p (o

)

Very broad distributions correlated with cell death

Narrower distributions correlated with viability

Pasquini, Hashmi, Sommer, Zimmerman (2012) and follow-up projects…

Project Examples

Nanotubes & Nanowires

Better dispersion of nanotubes (CNT) and nanowires (V2O5) à more uniform films with

better optical & electronic performance

Application: Transparent Batteries

Project Examples

with Azoz, Pasquini, Zimmerman, Pfefferle, et. al. with Gittleson, Taylor, et. al.

12 different experimental

treatments (CNT in water)

Precipitation & Aggregation

0 20 40 60 80 1000

100

200

300

400

500

time (minutes)

parti

cle

size

(nm

)

Aggregation of colloidal asphaltenes (PAH) with dispersants in oil

Dispersant can slow or halt aggregation

Precipitation of Iridium Oxide Nanoparticles during water oxidation

Crabtree Lab

Homogeneous  or  Heterogeneous  Iridium-­‐catalysis?  

Project Examples

THANK YOU!

Acknowledgments

Questions? Contact: WEB: LightScattering.yale.edu EMAIL: Sara.Hashmi@yale.edu OFFICE: Mason Lab 208A

Meny Elimelech Paul van Tassel Jongho Lee, Chanhee Boo Nawal Quennouz, Chinedum Osuji Leanne Pasquini, Seyla Azoz, Lisa Pfefferle, Julie Zimmerman Forrest Gittleson, Andre Taylor Crabtree Lab

Structure Function

Dynamics