Preparation and Characterization of Enantiomerically Pure Telechelic Diols from mcl−Poly[(R)-3-hydroxyalkanoates

Abstract

Novel enantiomerically pure telechelic OH-terminated poly[(R)-3-hydroxyoctanoate] (PHO-diol), poly[(R)-3-hydroxyoctanoate-co-poly[(R)-3-hydroxy-7-oxooctanoate] (PHOO-diol), and poly[(R)-3-hydroxyoctanoate-co-poly[(R)-3-hydroxy-7-octenoate] (PHUO-diol) have been synthesized in 80−91% yield from the corresponding high molecular weight polymers, respectively, by catalytic transesterification with ethylene glycol. The number average molecular weights (Mn) of these telechelic diols reached (2.0−3.0) × 103, which corresponds to 17−20 repeated monomer units. For PHOO-diol and PHUO-diol, the side chain functional groups remained, which provides with additional reactive groups for further polymerization or modification. The structures of the diols were confirmed by 1H NMR and IR spectra. The glass transition temperatures (Tg) of the telechelic diols are between −46 and −56 °C and the melting transition temperatures (Tm) are lower than 40 °C, all determined by DSC. These telechelic diols can be used as soft-segment...