Telechelic diols from poly[(R)-3-hydroxybutyric acid] and poly{[(R)-3-hydroxybutyric acid]-co-[(R)-3-hydroxyvaleric acid]}

We describe the preparation of telechelic OH-terminated poly[(R)-3-hydroxybutyric acid] (PHB) and poly( [(R)-3-hydroxybutyric acid]-co-[(R)-3-hydroxyvaleric acid]) (PHB/HV), on a semi-preparative scale, by a transesterification procedure from the high-molecular-weight polymers. The oligomers have well-defined reactive end groups and are well suited for the preparation of high-molecular-weight block copolymers by chain extension.