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Partially fluorinated poly(vinyl ether)s with C4F9 and C6F12H groups in the side chain were synthesized via living cationic polymerization in the presence of an added base in a fluorine-containing solvent, dichloropentafluoropropanes. For comparison, the polymerization of vinyl ether monomers with C2F5 and C6F13 groups and nonfluorinated monomers were also carried out. The characterization of the product polymers using size exclusion chromatography with a fluorinated solvent as an eluent indicated that all polymers had narrow molecular weight distributions (Mw/Mn ∼ 1.1). Interestingly, the moderately fluorinated polymers with C4F9 exhibited upper critical solution temperature-type phase separation in various organic solvents with wide-ranging polarities, whereas highly fluorinated polymers with C6F13 are insoluble in nonfluorinated solvents. Polymers with C4F9 groups exhibited temperature dependent solubility transitions not only in common organic solvents (e.g., toluene, chloroform, tetrahydrofuran, and acetone) but also in perfluoro solvents [e.g., perfluoro(methylcyclohexane) and perfluorodecalin]. On the other hand, the solubility of polymers with C6F12H showed completely different from that of polymers with C6F13, despite their similar fluorine content. In addition, various types of fluorinated block copolymers were prepared in a living manner. The block copolymers with a thermosensitive fluorinated segment underwent temperature-induced micellization and sol–gel transition in various organic solvents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Living cationic polymerization of fluorine-containing vinyl ethers [CH2CHOC2H4OC3H6CnF2n+1: 5FVE (n = 2), 13FVE (n = 6)] was investigated in various solvents with a CH3CH(OiBu)OCOCH3/Et1.5AlCl1.5 initiating system in the presence of an added base. 5FVE was polymerized quantitatively in toluene at 0 °C, and the obtained polymers had predetermined molecular weights with narrow molecular weight distributions (Mw/Mn < 1.1). On the other hand, for the polymerization of 13FVE, the product polymers precipitated due to their extremely poor solubility in nonfluorinated organic solvents. Therefore, fluorinated solvents such as hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroethers, or α,α,α-trifluorotoluene, as-yet uninvestigated for cationic polymerization, were employed. In these solvents, living polymerization was achieved even with 13FVE, yielding well-defined polymers (Mw/Mn < 1.1, by size exclusion chromatography using a fluorinated solvent as an eluent). The solvents were also shown to be good for living polymerization of isobutyl vinyl ether. The obtained fluorine-containing polymers underwent temperature-responsive solubility transitions in organic solvents. Poly(5FVE) showed sensitive upper critical solution temperature (UCST)-type phase separation behavior in toluene. Copolymers of 13FVE and isobutyl vinyl ether showed UCST-type phase separation in common organic solvents with different polarities depending on their composition, while a homopolymer of 13FVE was insoluble in all nonfluorinated organic solvents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011