This document summarizes chemical vapor deposition (CVD) methods for depositing thin polymer films. CVD involves evaporating monomers under vacuum and depositing the polymer film on a substrate. CVD allows conformal coatings on complex substrates and control over film properties. Applications include surface modification, microsensors, controlled release coatings, and responsive layers for chemical/biological detection.

1. Ayse Asatekina, Miles C. Barra, Salmaan H. Baxamusaa, Kenneth K.S. Laub, Wyatt Tenhaeffa, Jingjing Xua and Karen K. Gleasona,
Presented by:
Paula Soares Martins Antunes
Superfícies, Interfaces e Colóides
Mestrado Integrado em Engenharia Biomédica
5º ano, 2º semestre
07 /06/2010

2. Film polymerization methods
Emulsion
Bulk
Solution
Solution chemestry
fabricating surface modification by
polymer-based grafting desired functional
devices polymers

3. 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.
Polymerization (condensation reaction)
Monomer Monomer
Thin film
1 2
cured or annealed

4. A tissue paper substrate which
cannot survive exposure to
harsh solvents or high temperatures…
Without CVD
With CVD
PTFE
PTFE
A tissue before (a) and after (b) CVD surface modification
of a tissue with a 40 nm thickness of CVD
poly(tetrafluoroethylene) (PTFE).
A 40 nm thick CVD PTFE renders the
surface of the tissue non-wetting.
CVD Treatment Conventional sintering step
Room temperature 400 ºC

5. POLYMERIZATION VIA VAPOR DEPOSITION: WHAT WE HAVE
Advantages
• Film stress can be controlled
monomer by high/low frequency mixing
techniques
Low pressures • Control over stoichiometry
via process conditions.
reactor
bombardment
by free electrons
generating more
Electrons, ions, radicals, atoms,
and molecules in excited states
resulting in fragmentation of the monomer
and its
Deposition
through non-specific, complex
chemical reactions

6. POLYMERIZATION 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.

7. POLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGER
Initiated The heated gas surrounding the Oxidative the oxidant and monomer are
filaments creates the reactive species while the delivered to the substrate through the vapor
cooled substrate promotes the absorption of phase. Adsorption and spontaneous reaction
these species onto the growth surface proceed directly on the substrate. No additional
excitation of reactants is required

8. POLYMERIZATION VIA VAPOR DEPOSITION: THE YOUNGER
Acrylate polymer films PEDOT films (oCVD)
(iCVD)
Non planar substrates having micro
and/or nano scale features.
When microtrenches are solution coated with acrylate
polymers, the coating is non-conformal (f), as Large increases in adhesion strength are consistently
compared to conformal iCVD acrylate coating (g) observed. With this grafting technique, nanometer-scale
(down to 60 nm) PEDOT patterns can be obtained on flexible
conformal coatings substrates.
• polymeric thin films displaying uniform thickness over
the geometric features present in the substrate.

9. CVD POLYMERS APPLICATIONS
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 films
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

10. CVD POLYEMERS APPLICATIONS
Formation of the selective layers of composite membranes
This treatment prevents the coatings from delaminating through volume changes by over 10 times, as well as
ultrasonication.
Manufacture of micrometer scale resistive sensors
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).

11. CVD POLYMERS APPLICATIONS
Responsive layers that can transduce chemical and biological events into electrical
and/or optical responses
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.

12. SUMMARY