Synthesis of end-functionalized polymers and copolymers of cyclopentadiene with vinyl ethers by cationic polymerization

A series of cyclopentadiene (CPD)-based polymers and copolymers were synthesized by a controlled cationic polymerization of CPD. End-functionalized poly(CPD) was synthesized with the HCl adducts [initiator = CH3CH(OCH2CH2X)Cl; X = Cl (2a), acetate (2b), or methacrylate] of vinyl ethers carrying pendant functional substituents X in conjunction with SnCl4 (Lewis acid as a catalyst) and n-Bu4NCl (as an additive) in dichloromethane at -78 degreesC. The system led to the controlled cationic polymerizations of CPD to give controlled alpha -end-functionalized poly(CPD)s with almost quantitative attachment of the functional groups (F-n similar to 1). With the 2a or 2b/SnCl4/nBu(4)NCl initiating systems, diblock copolymers of 2-chloroethyl vinyl ether (CEVE) and 2-acetoxyethyl vinyl ether with CPD were also synthesized by the sequential polymerization of CPD and these vinyl ethers. An ABA-type triblock copolymer of CPD (A) and CEVE (B) was also prepared with a bifunctional initiator. The copolymerization of CPD and CEVE with 2a/SnCl4/n-Bu4NCl afforded random copolymers with controlled molecular weights and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight = 1.3-1.4). (C) 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 398-407, 2001.