MULTIFINCTIONAL COUPLING AGENTS FOR LIVING CATIONIC POLYMERIZATION .4. SYNTHESIS OF END-FUNCTIONALIZED MULTIARMED POLY(VINYL ETHERS) WITH MULTIFUNCTIONAL SILYL ENOL ETHERS

Telechelic (8) and end-functionalized four-arm star polymers (9) were synthesized through the coupling reactions of end-functionalized living poly(isobutyl vinyl ether) (5; DPBAR(n) approximately 10) with the bi- and tetrafunctional silyl enol ethers, H4-nC - [CH2OC6H4C(OSiMe3) = CH2]n (3: n = 2; 4: n = 4). The precursor polymers 5 were prepared by living cationic polymerization with functionalized initiators, CH3CH(Cl)OCH2CH2X (6), in conjunction with zinc chloride in methylene chloride at -15-degrees-C. The initiators 6 were obtained by the addition of hydrogen chloride gas to vinyl ethers bearing pendant functional groups X, including acetoxy [ - OC(O)CH3], styryl (- OCH2C6H4-p-CH = CH2), and methacryloyl [- OC(O)C(CH3) = CH2]. The coupling reactions with 3 and 4 in methylene chloride at -15-degrees-C for 24 h afforded the end-functionalized multiarmed polymers (8 and 9) in high yield (> 91%), where those with styryl or methacryloyl groups are new multifunctional macromonomers. (C) 1994 John Wiley & Sons, Inc.