Solventless grafting of functional polymer coatings onto Parylene C

In this work, the authors studied the use of vapor phase deposition to covalently attach functional polymer coatings onto Parylene C. Parylene C is important for several biomedical applications due to its inertness and biocompatibility; however, the surface properties are not ideal. The author modified the surface properties of Parylene C using a stepwise procedure in which a photoinitiator was first used to covalently attach a cross-linked anchoring layer to the Parylene C surface and then a thermal initiator was used to polymerize functional monomers onto the cross-linked anchoring layer. This process has several benefits because no solvents are used during the polymerization process. The generality of this procedure was demonstrated by depositing poly(vinyl pyrrolidone) and poly(ortho-nitrobenzyl methacrylate) as the functional polymers. Durability testing showed no loss in functionality or change in the elemental composition of the coating after sonication in methanol or long-term soaking in phosphate buffered saline solution. This process can be used to covalently attach a range of functionalities to Parylene C for potential use in biomedical applications.