Microphase Structure, Crystallization Behavior, and Wettability Properties of Novel Fluorinated Copolymers Poly(perfluoroalkyl acrylate-co-stearyl acrylate) Containing Short Perfluorohexyl Chains.

Abstract

Novel fluorinated copolymers of stearyl acrylate (SA) and (perfluorohexyl)ethyl acrylate (C6A), (perfluorohexyl)ethyl methacrylate (C6MA), 2-[[[[2-(perfluorohexyl)]-sulfonyl]methyl] amino]ethyl acrylate (C6SA), and methacrylate (C6SMA) were synthesized via miniemulsion copolymerization. The extremely hydrophobic monomers perfluoroalkyl acrylate (FA) and SA acted as the reactive costabilizer in the miniemulsion system. The microstructure and surface wetting properties of the copolymers were characterized by (1)H NMR, FT-IR, and dynamic contact angle test. The crystallization behaviors and fine surface structures of the copolymer films were determined by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) analysis. The self-assembled aggregation and roughness of the copolymer films were investigated by atomic force microscopy (AFM). The results showed that the fluorinated side chains interrupted and impeded the crystallizable side chains of SA from forming complete crystals. And the Tm and ΔHf of the copolymers were decreased as a consequence of this effect. The fluorinated side chains in P(C6A/SA) and P(C6MA/SA) arranged between the crystallizable hydrocarbon side chains of SA, while the crystallization structure of fluorinated and nonfluorinated pendant groups existed all at once in copolymers P(C6SA/SA) and P(C6SMA/SA). The four copolymers exhibited very low surface free energy and excellent dynamic water repellency attributed to the restriction of perfluoroalkyl groups combined with crystallization of stearyl pendant groups.