Polymer Thin Films and Surface Modification by Chemical Vapor Deposition: Recent Progress

Abstract

Chemical vapor deposition (CVD) polymerization uses vapor phase monomeric reactants to synthesize organic thin films directly on substrates. These thin films are desirable as conformal surface engineering materials and functional layers. The facile tunability of the films and their surface properties allow successful integration of CVD thin films into prototypes for applications in surface modification, device fabrication, and protective films. CVD polymers also bridge microfabrication technology with chemical and biological systems. Robust coatings can be achieved via CVD methods as antifouling, anti-icing, and antihydrate surfaces, as well as stimuli-responsive or biocompatible polymers and novel nanostructures. Use of low-energy input, modest vacuum, and room-temperature substrates renders CVD polymerization compatible with thermally sensitive substrates and devices. Compared with solution-based methods, CVD is particularly useful for insoluble materials, such as electrically conductive polymers and controllably crosslinked networks, and has the potential to reduce environmental, health, and safety impacts associated with solvents. This review discusses the relevant background and selected applications of recent advances by two methods that display and use the high retention of the organic functional groups from their respective monomers, initiated CVD (iCVD) and oxidative CVD (oCVD) polymerization.

Probing interfacial interactions of nafion ionomer: Thermal expansion of nafion thin films on substrates of different hydrophilicity/hydrophobicity

“…Polymer thin films of submicrometer thickness, supported on a substrate, are being exploited in a variety of industrial applications including electrochemical devices, microelectronics, protective coating, optoelectronics, and drug delivery . The structure and properties of such thin films are affected by confinement effects and interfacial interactions.…”

CVD Polymers for Devices and Device Fabrication

“…In this regard, CVD techniques introduced in the background are particularly suitable for integration into devices and processes for fabricating devices owing to their unique characteristics, including: i) solvent-free, ii) low temperature, iii) conformal deposition, iv) precise thickness control from nanometers to micrometers, v) versatile functionality due to the large selection of precursor library, and vi) readily scalable for large area depositions (Figure 1). [1,16,20,21] These CVD processes provide excellent compatibility to a wide range of substrates since there is no potential for solvent or plasma damage of the underlying material. The absence of wettability and surface tension renders CVD "substrate independent", meaning that modification of the process is not required for each different substrate.…”

“…[15] In addition to the aforementioned applications, defect-free CVD insulating, semiconducting, and insulating polymers have proved valuable in the fabrication of organic electronic devices. [1,[16][17][18][19][20][21] Among various CVD polymerization techniques, two distinct solvent-free CVD polymerization processes, initiated chemical vapor deposition (iCVD) and oxidative chemical vapor deposition (oCVD), have been developed by Gleason and co-workers. [1,16,20,21] In an iCVD process, volatile monomer(s) (e.g., acrylates) and an initiator (e.g., tert-butyl peroxide, TBPO) flow into the vacuum chamber which has temperature controlled chamber walls and substrates.…”

“…[1,[16][17][18][19][20][21] Among various CVD polymerization techniques, two distinct solvent-free CVD polymerization processes, initiated chemical vapor deposition (iCVD) and oxidative chemical vapor deposition (oCVD), have been developed by Gleason and co-workers. [1,16,20,21] In an iCVD process, volatile monomer(s) (e.g., acrylates) and an initiator (e.g., tert-butyl peroxide, TBPO) flow into the vacuum chamber which has temperature controlled chamber walls and substrates. The initiator is then broken apart to form radicals by thermal decomposition, [8] UV radiation [22] or plasma initiation.…”

“…[23] Aside from the iCVD and oCVD processes, plasma-enhanced chemical vapor deposition (PECVD), parylene CVD, molecular layer deposition (MLD), vapor deposition polymerization (VDP) and vapor phase polymerization (VPP) are additional common CVD polymerization processes. [1,16,20,21,24] PECVD and parylene CVD occur via a chain growth mechanism (radical polymerization), while in MLD, VDP and VPP, the monomers undergo a step-growth mechanism (condensation polymerization).Chemical vapor deposition (CVD) polymerization directly synthesizes organic thin films on a substrate from vapor phase reactants. Dielectric, semiconducting, electrically conducting, and ionically conducting CVD polymers have all been readily integrated into devices.…”