Influence of α-methyl group on molecular aggregation structure and surface physicochemical properties of fluoroalkyl side chain polymers

Abstract

Influence of α-methyl group on molecular aggregation states and surface physicochemical properties of poly(fluoroalkyl acrylate)s [PFA-Cy, where y is fluoromethylene number in Rf group] and poly(fluoroalkykl methacrylate)s [PFMA-Cy] thin films were systematically investigated. Spin-coated PFA-Cy and PFMA-Cy thin films were characterized by dynamic contact angle measurements and grazing-incidence wide-angle X-ray diffraction (GIWAXD) measurements. GIWAXD data revealed that fluoroalkyl side chains of PFA-Cy and PFMA-Cy with y≥8 formed regular structures in the surface region as well as bulk one. However, the degree of orientation and ordering of the Rf groups of PFMA-C8 thin films was low. Also, the receding contact angle (θr) of PFMA-C8 thin films was lower than that of PFA-C8 ones. By annealing treatment, the θr of PFMA-C8 was increased. These results suggest that the Rf groups of PFMA-C8 were disordered due to presence of the α-methyl group. The Rf groups became ordered to pack closely each other by annealing treatment, so that the water repellency was increased.