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