Designing polymer surfaces via vapor deposition
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Transcript of Designing polymer surfaces via vapor deposition
Presented by:
Ayse Asatekina, Miles C. Barra, Salmaan H. Baxamusaa, Kenneth K.S. Laub, Wyatt Tenhaeffa, Jingjing Xua and Karen K. Gleasona,
Paula Soares Martins Antunes
Superfícies, Interfaces e ColóidesMestrado Integrado em Engenharia Biomédica
5º ano, 2º semestre07 /06/2010
Bulk
Emulsion
Film polymerization methods
Solution chemestry
Solution
fabricating polymer-based
devices
surface modification by grafting desired functional
polymers
Chemical Vapor Deposition (CVD) is a technique
used to obtain a thin polymer film, typically
performed by evaporating monomers under
ultrahigh vacuum conditions and depositing a film
on a target substrate.
Monomer 1
Monomer 2
Thin film
Polymerization (condensation reaction)
cured or annealed
A tissue paper substrate which
cannot survive exposure to
harsh solvents or high temperatures…
Wit
hout C
VD
P
TFE
Wit
h C
VD
P
TFE
A tissue before (a) and after (b) CVD surface modification of a tissue with a 40 nm thickness of CVD
poly(tetrafluoroethylene) (PTFE).
Wit
hout C
VD
A 40 nm thick CVD PTFE renders the surface of the tissue non-wetting.
CVD Treatment Conventional sintering step
Room temperature 400 ºC
POLYMERIZATION VIA VAPOR DEPOSITION: WHAT WE HAVEPOLYMERIZATION VIA VAPOR DEPOSITION: WHAT WE HAVE
monomer
reactor
Low pressures
Advantages
• Film stress can be controlledby high/low frequency mixingtechniques• Control over stoichiometry
via process conditions.
bombardmentby free electrons
generating more
Electrons, ions, radicals, atoms, and molecules in excited states
fragmentation of the monomer
and itsDeposition
through non-specific, complex
chemical reactions
resulting in
POLYMERIZATION VIA VAPOR DEPOSITION: WHAT WE HAVEPOLYMERIZATION VIA VAPOR DEPOSITION: WHAT WE HAVE
Do not use:
• plasma
• an initiator specie (thermal initiator/photo initiator)
• an oxidative specie.
• VDP
• both monomers enter the chamber simultaneously
• MDP
• sequential, alternating sequence of monomers for better control over film growth.
• an oxidative specie.
POLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGERPOLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGER
Initiated The heated gas surrounding the
filaments creates the reactive species while the
cooled substrate promotes the absorption of
these species onto the growth surface
Oxidative the oxidant and monomer are
delivered to the substrate through the vapor
phase. Adsorption and spontaneous reaction
proceed directly on the substrate. No additional
excitation of reactants is required
PEDOT films (oCVD)
POLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGERPOLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGER
Acrylate polymer films
(iCVD)
Large increases in adhesion strength are consistentlyobserved. With this grafting technique, nanometer-scale(down to 60 nm) PEDOT patterns can be obtained on flexiblesubstrates.
When microtrenches are solution coated with acrylatepolymers, the coating is non-conformal (f), ascompared to conformal iCVD acrylate coating (g)
Non&planar substrates having micro&and/or nano&scale features.
conformal coatings
• polymeric thin films displaying uniform thickness over the geometric features present in the substrate.
CVD CVD POLYMERSPOLYMERS APPLICATIONSAPPLICATIONS
Synthetic control over the functional groups displayed at the surfaces
• surface attachment of fluorescent dyes, bioactive molecules, and inorganic nanoparticles.
• copolymerization with monomers with multiple vinyl groups results in controllably cross-linked filmswhich are resistant to solvent damage yet remain mechanically flexible.which are resistant to solvent damage yet remain mechanically flexible.
• coat microparticles to encapsulate them for controlled release, and change their surface chemistry.
Conventional methods iCVD
Aggregation of the small particles Solvent-free
Fragility of drug molecules Room temperature
Potential solubility of drug molecules
CVD CVD POLYEMERSPOLYEMERS APPLICATIONSAPPLICATIONS
This treatment prevents the coatings from delaminating through volume changes by over 10 times, as well as
ultrasonication.
Formation of the selective layers of composite membranes
In these applications, the swelling of a thin, CVD-deposited polymer layer to the
analyte of interest is converted into a change in electrical resistance.:
• Inorganic microcantilever coated with a CVD-polymerized layer that reacts with
amines. This results in the swelling of the polymer, which causes the cantilever to
deflect and complete a circuit
• Microtrenches coated with a conformal layer of poly(4-vinyl pyridine) (P4VP).
Manufacture of micrometer scale resistive sensors
CVD CVD POLYMERSPOLYMERS APPLICATIONSAPPLICATIONS
Changes in film thickness can result from swelling upon
exposure to a specific analyte, or switching of the surface
energy can occur in response to a change in temperature,
external field, or pH.
Responsive layers that can transduce chemical and biological events into electrical
and/or optical responses
SUMMARYSUMMARY