SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTAL POLYMERS BY LIVING RING-OPENING METATHESIS POLYMERIZATION .4. SYNTHESIS OF AB BLOCK COPOLYMERS CONTAINING AMORPHOUS AND SIDE-CHAIN LIQUID-CRYSTAL BLOCKS

This paper describes the synthesis of AB type block copolymers that contain a side chain liquid crystalline polymer (SCLCP) block and an amorphous polymer block by living ring-opening metathesis polymerization employing Mo(CH-t-Bu)(NAr)(O-t-BuU)2 (Ar = 2,6-C6H3-i-Pr2) as the initiator. Norbornene, 5-cyano-2-norbornene, and methyltetracyclododecene were used for the amorphous polymer blocks and n-[((4'-methoxy-4-biphenyl)yl)oxy]alkyl bicyclo[2.2.1]hept-2-ene-5-carboxylates (1-n, n = 3, 6) were used for the SCLCP block. Block copolymers with monomer ratios from 75/25 to 20/80 (amorphous/SCLCP) and narrow molecular weight distributions (M(w)/M(n) = 1.06-1.25) were obtained in high yield. Glass transition temperatures of each block and the isotropization temperature of the mesophase are independent of the composition of the block copolymer and the same as those of the respective homopolymers. The enthalpy change of isotropization decreases significantly when the amorphous polymer block has a T(g) higher than the isotropization temperature and the content of SCLCP is less than 60-70%.