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) × 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 1 H NMR and IR spectra. The glass transition temperatures ( T g ) of the telechelic diols are between −46 and −56 °C and the melting transition temperatures ( T m ) are lower than 40 °C, all determined by DSC. These telechelic diols can be used as soft-segments to prepare novel block copolymers with desired properties.