• ring-opening polymerization;
  • crystallization;
  • crystalline morphologies;
  • hydrophilicity;
  • nonlinear block copolymers


Novel, well-defined A4BA4 nonlinear block copolymers [poly(ϵ-caprolactone)]4-block-poly(propylene oxide)-block-[poly(ϵ-caprolactone)]4 (PCL4-b-PPO-b-PCL4) with eight arms were synthesized by ring-opening polymerization. An investigation of melting and crystallization demonstrated that the values of crystallization temperature, melting temperature and degree of crystallinity of PCL4-b-PPO-b-PCL4 were enhanced with an increase of PCL chain length. At the same time, the crystallizability of PCL segments was influenced by the star-shaped structure of the copolymers and the amorphous PPO segments in the copolymers. Furthermore, PCL4-b-PPO-b-PCL4 showed crystalline morphologies that were different from that of linear PCL according to polarized optical microscopy. Moreover, the hydrophilicity of the copolymers could be improved and adjusted by the star-shaped structure and the alteration of the relative content of the PCL and PPO segments in the copolymers.© 2013 Society of Chemical Industry