Facile Synthesis of Fluorinated Polyacrylate Elastomer via Emulsion Polymerization Using Adjustable Amphiphilic Star Macro-RAFT Agent as Surfactant

Novel thermoplastic fluorinated polyacrylate films possessing excellent mechanical performance are prepared by emulsion polymerization latex using adjustable amphiphilic star macro-reversible addition-fragmentation chain-transfer (macro-RAFT) agent as surfactants in this work. First, star macro-RAFT agent equipped with six amphiphilic arms is synthesized via two-step RAFT polymerization of acrylic acid (AA) and 2,2,2-trifluoroethyl acrylate (TFEA) in the presence of hexa-functional RAFT agents. The surface activities of the as-synthesized amphiphilic star macro-RAFT agents in aqueous solutions are studied. Subsequently, various fluorinated polyacrylate latexes are obtained by conducting emulsion polymerization of 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) and butyl acrylate (BA) using the amphiphilic star macro-RAFT agents as both RAFT agents and surfactants. The latex particle morphologies are studied by transmission electron microscope (TEM) and particle size is measured by dynamic light scattering (DLS). The effects of PAA segment length, HFBA/BA mole ratio, and TFEA segment length on the surface morphologies of the fluorinated polyacrylate films are illustrated by investigating the surface properties using water contact angle test and atomic force microscopy (AFM). Finally, the elastomeric films obtained by directly casting the prepared fluorinated polyacrylate latexes show excellent comprehensive properties such as tensile strength over 4 MPa, elongation at break approximate to 700%, permanent deformation below 25%. Water absorption test is also provided as a reference.