Bio-based Branched Polymer Bearing Castor Oil Core as a Nucleating Agent for Poly(l-Lactic Acid)

In this study, a bio-based branched polymer bearing a castor oil core was synthesized, and the nucleating effect of the branched polymer on the crystallization of poly(l-lactic acid) (PLLA) was investigated by a differential scanning calorimetry and a polarized optical microscopy. The bio-based branched polymer was synthesized by ring-opening polymerization of l-lactide using castor oil core as an initiator, and subsequently modification of terminal groups was performed. A small amount of the trimellitoyl-terminated branched polymer accelerated the crystallization of PLLA, and the crystallization half time was dependent on the molecular weight of the branched polymer. By the addition of the branched polymer, the spherulite size of PLLA became much smaller than that of neat PLLA. Furthermore, the strain at break of PLLA containing the branched polymer was improved, compared with that of neat PLLA.