First amphiphilic poly(vinylidene fluoride-co-3,3,3-trifluoropropene)-b- oligo(vinyl alcohol) block copolymers as potential nonpersistent fluorosurfactants from radical polymerization controlled by xanthate

摘要

The synthesis of poly(vinylidene fluoride-co-3,3,3-trifluoropropene)-b- oligo(vinyl alcohol) block copolymers by sequential controlled radical copolymerization of vinylidene fluoride (VDF) and 3,3,3-trifluoropropene (TFP) and of vinyl acetate in the presence of xanthate and their use as original surfactants are presented. First, a fluorinated xanthate C_6F _(13)C_2H_4OC(O)CH(CH_3)SC(S)OC _2H_5 was prepared in two steps from ~1H,~1H,2H,2H- perfluorooctanol in 67% overall yield. Then, it was successfully involved as a chain transfer agent for the macromolecular design via the interchange of xanthates (MADIX) polymerization of vinyl acetate in a fluorinated solvent in 71% yield, and a good agreement was noted between targeted and experimental molecular weights of poly(vinyl acetate). This fluorinated xanthate was also successfully used in the radical copolymerization of VDF and TFP. Then, these poly(VDF-co-TFP) copolymers bearing a xanthate end group were involved in the controlled radical polymerization of vinyl acetate (VAc) leading to poly(VDF-co-TFP)-b-oligo(VAc) block copolymers. All the structures of the obtained intermediates and copolymers were characterized by NMR spectroscopy and size exclusion chromatography to assess the molar contents of VDF, TFP, and VAc and the molecular weights and polydispersity indices. The results show, particularly in the case of the direct radical terpolymerization, that VAc and VDF are the most and the least reactive monomers, respectively. The acidic hydrolysis of poly(VAc) sequences of the block copolymers into oligo(vinyl alcohol) led to original water-soluble surfactant, the surface tension of which (27 mN m~(-1) at 7.2 g L~(-1)) was comparable to that of ammonium perfluorooctanoate (APFO) and thus appears as potential alternative to APFO surfactant.