Synthesis of poly(beta-pinene)-b-polytetrahydrofuran from beta-pinene-based macroinitiator

The living cationic polymerization of beta -pinene was carried out with 1-p henylethyl chloride/Ti(OiPr)(4)/TiC4 Ti(OiPr)(4)/TiCl4 mole ratio 1:3) in t he presence of nBu(4)NCl in CH2Cl2 at -40 degreesC. Styrene was added to ca p the living poly(beta -pinene) just before beta -pinene had been consumed almost completely (conversion similar to 98%) and then the reaction was sto pped at low conversion of styrene to give beta -pinene macroinitiator with benzyl chloride terminal. H-1 NMR analysis of the obtained polymer showed t hat one macroinitiator possessed almost one benzyl chloride end group. The macroinitiator in conjunction with silver salt, AgClO4 or AgSbF6, could rea dily initiate the ring-opening polymerization of THF in the presence of sma ll amounts of propylene oxide. The macroinitiator/AgSbF6 system gave an alm ost pure block copolymer of beta -pinene/THF (weight content: 45% for beta -pinene segments and 55% for THF segments) with a relatively narrow molecul ar weight distribution. In contrast, homopolyTHF and unblocked macroinitiat or formed along with the block copolymer with the macroinitiator/AgClO4 sys tem owing to the competing side reactions. (C) 2001 Elsevier Science Ltd. A ll rights reserved.