Formation of stable polydopamine layer on polytetrafluoroethylene substrate by hybrid process involved plasma treatment and spontaneous chemical reactions

Abstract

A hybrid process for the surface modification of polytetrafluoroethylene (PTFE) involving plasma pretreatment and spontaneous chemical reaction of polydopamine (PDA) was examined. This process could effectively prepare a stable PDA layer on the plasma-treated PTFE substrate. For analyzing the chemical reactions to form stable PDA layer, we confirmed the surface chemical reactions by spectroscopies and proposed a possible reaction process between dopamine and the plasma-treated PTFE surface. Moreover, it was found that a simple drying procedure could be promoted chemical bond formation between the plasma-treated PTFE and the PDA layer. The PDA layer was proved to be highly durable under harsh chemical conditions including both strongly acidic and basic conditions. The surface was proved to be robust and available for further functionalization by surface-initiated atom transfer radical polymerization (ATRP) of other monomers. The stability of the PDA layer was enough stable for immobilizing ATRP initiator and following polymerization process, that is, activator regenerated by electron transfer ATRP of methacrylate monomer could be initiated from the initiator at the surface. Overall, this procedure achieved practical and reliable surface functionalization of PTFE substrates, and would expand the potential applications of PTFE substrates in various industrial fields, including medicine.