Synthesis and characterization of a novel star shaped rod-coil block copolymer

A novel star shaped rod-coil block copolymer, tri-armed star poly (epsilon- caprolactone)-b-poly {2,5-bis[(4-methoxyphenyl) oxycabony] styrene} [S-(PCL-b-PMPCS)(3)], was successfully synthesized via atom transfer radical polymerization in chlorobenzene solution using macro-initiator and CuBr/Sparteine complex as catalyst. The results showed that the number average molecular weigh M-n was increased versus monomer conversion, and that the polydispersities M-w/M-n was quite narrow (<1.35), which were the character of controlled polymerization. The structure of the star shaped block copolymers was experimentally confirmed by H-1 NMR. The liquid crystalline behavior of them was studied using DSC and POM. The star shaped block copolymer with low molar percentage of PMPCS block could show T-m of PCL. And only those copolymers with long rigid segment PMPCS could form liquid crystalline phase which was quite stable with a high clearing point.