Synthesis and characterization of ABA-triblock copolymers with poly(ethylene glycol) segments and LC-segments

This paper describes the synthesis of ABA-triblock copolymers with poly(ethylene glycol) A-blocks and a liquid crystalline polyester B-block. Three block copolymer series are presented with different block length of A- and B-blocks. The block copolymers show thermotropic liquid crystalline behavior up to a content of poly(ethylene glycol) segments of 50 wt%. Depending on their composition and chain length, the block copolymers are microphase separated or non-microphase separated. In the microphase separated block copolymers the poly(ethylene glycol) segments are able to crystallize. The degree of crystallinity and the spherulite diameter is strongly influenced by the length of the poly(ethylene glycol) segment itself as well as by the length of the incorporated polyester segment. Received: 19 December 1997/Revised version: 22 December 1997/Accepted: 22 December 1997