Well-adhered, conformal, thin (<100 nm) coatings can easily be obtained by chemical vapor deposition (CVD) for a variety of technological applications. Room temperature modification with functional polymers can be achieved on virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. In CVD polymerization, the monomer(s) are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, and thickness control. Initiated-CVD shows successful results in terms of rationally designed micro- and nanoengineered materials to control molecular interactions at material surfaces. The success of oxidative-CVD is mainly demonstrated for the deposition of organic conducting and semiconducting polymers.

Preferred crystallographic orientation (texture) in thin films of technologically important materials frequently has a strong effect on the properties of these films and is important for stable surface properties. The deposition of organized molecular films of a poly‐perfluorodecylacrylate, poly‐(1H,1H,2H,2H‐perfluorodecyl acrylate) (p‐PFDA), by initiated chemical vapor deposition (iCVD) is described. The tendency of p‐PFDA to crystallize in a smectic B phase has been reported in films prepared from solution but not for those using a CVD technique. The degree of crystallinity and the preferred orientation of the perfluoro side chains, either parallel or perpendicular to the surface, are controlled by tuning the CVD process parameters (i.e., initiator to monomer flow rate ratio, filament temperature, and substrate temperature). Films with no observable X‐ray diffraction patterns are also achieved. The observed differences in crystal texture strongly impact the observed water contact angles (150° to 130°, advancing) and corresponding hysteresis behavior. Low hysteresis (<7°) is associated with high crystallinity, particularly when the orientation of the crystallites resulted in the perfluoro side groups being oriented parallel to the surface. The latter texture resulted in smoother film than the texture with the chains oriented perpendicular to the surface and this can be very advantageous for applications in which relatively smooth but still crystalline films are needed.

Polymers with their tunable functionalities offer the ability to rationally design micro- and nano-engineered materials. Their synthesis as thin films have significant advantages due to the reduced amounts of materials used, faster processing times and the ability to modify the surface while preserving the structural properties of the bulk. Furthermore, their low cost, ease of fabrication and the ability to be easily integrated into processing lines, make them attractive alternatives to their inorganic thin film counterparts. Chemical vapor deposition (CVD) as a polymer thin-film deposition technique offers a versatile platform for fabrication of a wide range of polymer thin films preserving all the functionalities. Solventless, vapor-phase deposition enable the integration of polymer thin films or nanostructures into micro- and nanodevices for improved performance. In this review, CVD of functional polymer thin films and the polymerization mechanisms are introduced. The properties of the polymer thin films that determine their behavior are discussed and their technological advances and applications are reviewed.

This report describes the preparation of superhydrophobic and oleophobic surfaces by grafting of poly(perfluorodecylacrylate) chains with initiated chemical vapor deposition on silicon substrates. The grafting enhances the formation of a semicrystalline phase. The crystalline structures reduce the polymer chain mobility, resulting in nonwetting surfaces with both water and mineral oil. On the contrary, the same contacting liquid easily wets the amorphous ungrafted polymer.

Proton conductive copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (PFDA) and methacrylic acid (MAA) have been synthesized by initiated chemical vapor deposition (iCVD). Detailed insights into the copolymers’ molecular organization were gained through an X-ray-based investigation to serve as a starting point for systematic studies on the relation among proton conductivity and polymer structure. The method of copolymerization, iCVD, facilitated the tuning of the ratio between acidic −COOH groups, coming from MAA, and the hydrophobic matrix from the PFDA components. It was demonstrated that the copolymers crystallize into a bilayer structure, formed by the perfluorinated pendant chains of PFDA, perpendicular to the substrate surface. The MAA molecules form COOH-enriched regions among the bilayersparallel to the substrate surfacewhich can act as ionic channels for proton conduction when the acid groups are deprotonated. The interplanar distance between the bilayer lamellar structures increases by the presence of MAA units from 3.19 to 3.56 nm for the MAA–PFDA copolymer with 41% MAA, therefore yielding to 0.4 nm wide channels. Proton conductivities as high as 55 mS/cm have been achieved for copolymers with 41% MAA fraction. Such ordered, layered nanostructures were never shown before for copolymers deposited from the vapor phase, and their anisotropy can be of inspiration for many applications beyond proton conduction. Moreover, the one-step copolymerization process has the potential to manufacture inexpensive, high quality membranes for proton exchange membrane fuel cells.