Synthesis of cross-linkable fluorinated core–shell latex nanoparticles and the hydrophobic stability of films

Abstract

Core–shell structured latex nanoparticles containing perfluoroalkyl and cross-linkable groups in the shell layer are prepared by two-step emulsion polymerization method. Specifically, the emulsion copolymerization of isobornyl methacrylate (IBOMA) and butyl acrylate (BA) leads to core particle, on which the mixture of IBOMA, BA and fluorinated acrylate monomer is copolymerized with glycidyl methacrylate and acrylic acid, respectively, to generate epoxy- and carboxyl-containing fluorinated latex nanoparticles. The contents of fluorine and cross-linkable monomer are adjusted over a range from 0 to 12 wt%, and from 0 to 20 mol%, respectively. The core–shelled nanostructures of latex particles are confirmed by dynamic light scattering and high-resolution TEM. After thermal treatment, the cross-linked films exhibit significantly improved thermal and hydrophobic stability. Moreover, it is found that, in comparison with the non-cross-linked film, a suitable cross-linking degree is advantageous for the segregation of fluorinated groups on the film surface. The cross-linked film with 6 wt% fluorine exhibits a low surface tension of 17.7 mN/m, even lower than that of polytetrafluoroethylene (18.5 mN/m), owing to the high enrichment of fluorine, as evidenced by XPS, ATR-FTIR and AFM measurements.