Preparation and characterization of enantiomerically pure telechelic diols from mcl-poly[(R)-3-hydroxyalkanoates]

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 (M-n) of these telechelic diols reached (2.0-3.0) x 10(3), 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 H-1 NMR and IR spectra. The, glass transition temperatures (T-g) of the telechelic diols are between -46 and -56 degreesC and the melting transition temperatures (T-m) are lower than 40 degreesC, all determined by DSC. These telechelic diols can be used as soft-segments to prepare novel block copolymers with desired properties.