Initiated chemical vapor deposition of polymer coatings with different wettability for biological and environmental applications

Surface wettability is a crucial characteristic that dictates the practical application of a solid surface. To tailor the wettability of substrates as needed for specific environmental and biological applications, polymer coating has been widely used as a versatile surface modification method. Conventional methods of polymer coating are usually conducted in the liquid phase with the presence of various organic chemicals. After the wet chemical process, irregular and defective coatings are often formed due to the surface tension of the solution, posing the risks of changing the morphology and compromising the functionalities of substrates undesirably. In addition, the organic residues from the solution bring biosafety concerns, which need to be removed in extra operations. Initiated chemical vapor deposition (iCVD) represents a solution-free surface modification that can fabricate various polymer coatings with different wettabilities, and have the advantage of creating smooth and flawless coatings at the nanoscale. Here we apply iCVD modification in oil/water separation, drug delivery, and anti-bioadhesion to solve the problems that occur in using traditional surface modifications. Firstly, metal meshes were modified to be superhydrophilic for oil-water separation by iCVD grafting of double-layer nanocoating with a highly crosslinked base and enriched surface hydrophilic chains. The grafted mesh demonstrated improved surface wetting and preserved mesh openings, which contributed to high separation flux. The highly crosslinked base of nanocoating ensured the durability of modified mesh through repeated separations and even after harsh treatments. Secondly, superhydrophobic fluoropolymer coatings with hierarchical roughness were fabricated by combining iCVD steps with varying monomer saturation ratios. The adhesion of biomolecules was significantly reduced on this superhydrophobic coating, which could work as a surface modification for different medical devices to solve the bioadhesion-induced blood coagulation problem. Thirdly, hydrophilic polymer coatings deposited via iCVD were employed to encapsulate different drugs on medical devices. The burst drug release from medical devices was eliminated because the all-dry iCVD prevented the drug migration into encapsulation coatings that commonly occurred in the solution-based encapsulation processes. A wide range of drug release rates was achieved by regulating the thickness of encapsulation coatings and drug dose density. To work as the stent encapsulations, the stretchability of nanocoatings was improved by lowering their crosslinking degree, which solved the problem of coating damage during the stent dilation. In addition, the ultrasmooth nature of iCVD coating enabled outstanding blood compatibility by suppressing the adhesion of platelets. In summary, this vapor-based deposition effectively modifies the surfaces of diverse devices to change their wettability for different purposes and shows great potential in environmental and biological applications.