Synthesis of CO2-philic Xanthate-Oligo(vinyl acetate)-Based Hydrocarbon Surfactants by RAFT Polymerization and Their Applications on Preparation of Emulsion-Templated Materials

Amphiphilic block copolymers poly(ethylene glycol)-block-oligo(vinyl acetate) (PEG b OVAc) and OVAc-b-PEG-b OVAc have been demonstrated to be effective surfactants for CO2 in-water (C/W) emulsions However, the high cost and difficulty of synthesis process can render the economics of CO2 process unfavorable In this work, by reversible addition fragmentation chain transfer (RAFT) polymerization, a series of well-defined CO2 philic triblock copolymers X-OVAc b-PEG-b-OVAc-X (where X stands for xanthate group) were synthesized The structures and molecular weights of these copolymers were characterized by H-1 NMR and GPC The results of GPC analysis exhibited relatively narrow polydispersity (PDI < 1 35) The process of preparation of X-OVAc based surfactants was much more simple, inexpensive and also easy to control, which could promote industrial-scale applications The X-OVAc-based surfactants were found effectively to produce highly concentrated stable C/W emulsions Porous emulsion-templated materials were prepared by the polymerization of the continuous phase of C/W emulsions The open-cell morphology of the emulsion templated materials was evidenced by scanning electron microscope To tune the morphology of the porous structures, the influence of the surfactant concentration and molecular weight of OVAc block were also investigated It was shown that X-OVAc-based surfactants can outperform perfluorinated surfactants and approach OVAc based surfactants for such applications