Non-crosslinked fluorinated copolymer particles stabilized Pickering high internal phase emulsion for fabrication of porous polymer monoliths

Abstract

Preparation of Pickering High internal phase emulsion (HIPE) is a challenging task mainly due to the requirement of predominant hydrophobicity or hydrophilicity of the particles. In this study, for the first time, we report the use of fluorinated copolymer particles (FCPs) as an effective stabilizer for water in oil (w/o) Pickering HIPEs. FCPs as stabilizers eliminate the need of hydrophobic/hydrophilic modification of particles, co-stabilizer and/or stringent experimental conditions in the synthesis of Pickering HIPEs. Reversible addition-fragmentation chain transfer (RAFT) polymerization is employed to synthesize FCPs, (poly(dodecafluoroheptyl methacrylate)-b-poly(methyl methacrylate) (PDFMA-b-PMMA) by using 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as RAFT agent. FCPs acted as a mechanical barrier at w/o interface and in turn prevented droplet coalescence in Pickering HIPEs. The prepared HIPEs demonstrated good stability against elevated temperature and did not phase separated during free radical polymerization. In addition, porous polymeric monoliths were obtained whose morphology and pore sizes were tuned by simply varying the amount of FCPs and/or internal phase contents.