Precise Design of Surface Nano-texture and Surface Chemistry of Polymeric Solids

Abstract

Surface properties of polymeric materials were controlled by fabrication of nano-structure and submicronorder structure of poly(fluoroalkyl acrylate) using the chemical and physical surface modification techniques. The relationship between the ordered structure of fluoroalkyl (R f) groups and water repellency mechanism was precisely investigated by grazing-incidence X-ray diffraction, water contact angle measurements and X-ray photoelectron spectroscopy. It was revealed that poly{2-(perfluorooctyl)ethyl acrylate} (PFA-C8) was crystallized and formed ordered structure to result in high water repellency. Surface nano-texturing onto PFA-C8 film surface was carried out using an anodic aluminum oxide (AAO) membrane as a mold. The nano-texture of AAO mold with a pore diameter of 200 nm was transformed onto the PFA-C8 film surface to fabricate nano-structure, which revealed high water and oil repellency. On the other hand, various types of monomers were grafted on the solid surface through surface-initiated atom transfer radical polymerization to result in high-density polymer brushes. Hydrophobic PFA-C8brush surface revealed a low friction coefficient and a good wear resistance. Water lubrication and low friction were observed on the hydrophilic polymer brush. These polymer brushes were successfully introduced on the commercial fluoropolymer, which has inherent radical initiator functional groups. These results indicated that nano-layer immobilization through surface-initiated polymerization and surface texturing are promising methods to control the surface chemistry and surface structure at dimensions in the nano-meter range.