Cationic Copolymerization of 1,3-Pentadiene with Isoprene

The cationic copolymerization of 1,3-pentadiene (PD) with isoprene (IP) initiated by AICl3, was carried out in toluene. The microstructure of the copolymer chain was characterized by IR and 1H NMR. IP is incorporated in the copolymer chain mainly in cyclic segments. The PD–IP copolymer has a much higher cyclic content than the PD homopolymer, which shows that the cyclization reaction during PD polymerization is enhanced by the addition of IP. In addition, the reactivity ratios for IP(M1) and PD(M2) determined by the Kelen–Tudos method from low-conversion data are r1 = 1.22 and r2 = 1.09.