High Glass Transition Temperature Fluoropolymers for Hydrophobic Surface Coatings via RAFT Copolymerization

Abstract

The preparation of polymer thin films or surface coatings that display a static water contact angle >95° often requires hierarchical roughness features or surface functionalization steps. In addition, inherently hydrophobic polymers such as fluoropolymers often possess low glass transition temperatures, reducing their application where thermal stability is required. Herein, the first reported synthesis of 2,3,4,5,6-pentafluorostyrene (PFS) and N-phenylmaleimide (NMI) via reversible addition–fragmentation chain-transfer (RAFT)-mediated free radical polymerization is presented, with a view towards the preparation of inherently hydrophobic polymers with a high glass transition temperature. A suite of copolymers were prepared and characterized, and owing to the inherent rigidity of the maleimide group in the polymer backbone and π–π interactions between adjacent PFS and NMI groups, very high glass transition temperatures were achieved (up to 180°C). The copolymerization of N-pentafluorophenylmaleimide was also performed, also resulting in extremely high glass transition temperature copolymers; however, these polymers did not exhibit characteristics of being under RAFT control. Thin films of PFS-NMI copolymers exhibited a static contact angle ~100°, essentially independent of the amount of NMI incorporated into the polymer.