Synthesis of β-Pinene/THF Block Copolymers

The living cationic polymerization of β-pinene was carried out with α-chloroethylbenzene(PEC)/TiCl₄/Ti(OiPr)₄ initiating system in CH₂C1₂ at -40℃. After 25 min of reaction(β-pinene conversion~100%),the resulted living poly(β-pinene) was capped with a few units of styrene and then the polymerization was quenched to give β-pinene macroinitiator with benzenyl chloride chain end (P(β-p)-St-Cl). The structure of the macroinitiator was confirmed by ¹H NMR (Fig.l). The macroinitiator, in conjunction with AgSbF₆ or AgC1O₄,was used to initiate the ring-opening cationic polymerization of THF in the presence of propylene oxide promoter. GPC analysis of the obtained polymers showed that AgSbF₆ system led to almost pure block copolymers of β-pinene with THF, whereas AgC1O₄ system gave mixtures of block copolymers and low molecular weight homopolymers of THF and unreacted macroinitiator (Fig.2). ¹H NMR analysis further confirmed the formation of β-pinene/THF block copolymers with macroinitiaor/AgSbF₆ system (Fig.3).