Chemical vapor deposition (CVD) polymerization utilizes the delivery of vapor-phase monomers to form chemically well-defined polymeric films directly on the surface of a substrate. CVD polymers are desirable as conformal surface modification layers exhibiting strong retention of organic functional groups, and, in some cases, are responsive to external stimuli. Traditional wet-chemical chain- and step-growth mechanisms guide the development of new heterogeneous CVD polymerization techniques. Commonality with inorganic CVD methods facilitates the fabrication of hybrid devices. CVD polymers bridge microfabrication technology with chemical, biological, and nanoparticle systems and assembly. Robust interfaces can be achieved through covalent grafting enabling high-resolution (60 nm) patterning, even on flexible substrates. Utilizing only low-energy input to drive selective chemistry, modest vacuum, and room-temperature substrates, CVD polymerization is compatible with thermally sensitive substrates, such as paper, textiles, and plastics. CVD methods are particularly valuable for insoluble and infusible films, including fluoropolymers, electrically conductive polymers, and controllably crosslinked networks and for the potential to reduce environmental, health, and safety impacts associated with solvents. Quantitative models aid the development of large-area and roll-to-roll CVD polymer reactors. Relevant background, fundamental principles, and selected applications are reviewed.

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.

We report the single-step preparation of controllably cross-linked poly(divinylbenzene) (PDVB) and poly(4-vinylpyridine-co-divinylbenzene) thin films using initiated chemical vapor deposition (iCVD). Fourier transform infrared spectroscopy-based methods for quantifying film composition and degree of cross-linking are elucidated; the validity of these methods is assessed using X-ray photoelectron spectroscopy and nanoindentation. The extent of reaction of divinylbenzene (DVB) pendant vinyl bonds in homo- and copolymer films is unaffected by changes in initiator concentration, suggesting that bond reactivity, rather than radical concentration, is the limiting factor. Analysis of film step coverage (S) over high aspect ratio (AR) features and sticking probability calculations lend insight into the reactivity of both monomers and explain the extreme conformality of PDVB films (S = 0.87 ± 0.02 at AR = 4.7). In addition, the incorporation and cross-linking of DVB moieties in the copolymer are extremely reproducible and can be used to tune the elastic moduli of the films from 3.4 to 5.8 GPa.

Chemical vapor deposition (CVD) of polymer films represent the marriage of two of the most important technological innovations of the modern age. CVD as a mature technology for growing inorganic thin films is already a workhorse technology of the microfabrication industry and easily scalable from bench to plant. The low cost, mechanical flexibility, and varied functionality offered by polymer thin films make them attractive for both macro and micro scale applications. This review article focuses on two energy and resource efficient CVD polymerization methods, initiated Chemical Vapor Deposition (iCVD) and oxidative Chemical Vapor Deposition (oCVD). These solvent‐free, substrate independent techniques engineer multi‐scale, multi‐functional and conformal polymer thin film surfaces and interfaces for applications that can address the main sustainability challenges faced by the world today.

A simple, efficient, and scalable method for patterning microstructures on curved substrates is demonstrated. Initiated chemical vapor deposition is used to synthesize a thin film that crosslinks upon UV exposure. Polymeric features are defined on glass rods with high curvature and used as masks for metal patterning. Additionally, vapor-deposited polymer layers are selectively patterned to produce bifunctional surfaces.