LIQUID-CRYSTALLINE POLY(VINYL ETHER)S AND BLOCK COPOLY(VINYL ETHER)S BY LIVING CATIONIC POLYMERIZATION

A series of liquid crystalline (LC) poly(vinyl ether)s 1 was prepared by living cationic polymerization of a mesogenic vinyl ether monomer, 4-butoxyphenyl 4-((6-vinylhexyl)oxy)benzoate (11), in the presence of the HI/I-2 (1/1 mol/mol) initiating system. The number average molar m ass of polymers 1 increased linearly with the initial monomer to initi ator molar ratio (M(a) = 3000-15 000 g mol(-1), DPn approximate to 5-5 0), according to the living character of the polymerization, and their molar mass distribution was rather narrow (M(w)/M(n) = 1.10-1.15). Fu rthermore, two sets of AB diblock copoly(vinyl ether)s 2 and 3 were pr epared by sequential polymerization of vinyl ether 11 and isobutyl vin yl ether (12) and chiral (S)-2-methylbutyl vinyl ether (13) respective ly, by using the same HI/I-2 system. While the average degree of polym erization of the LC block was kept constant (DPn approximate to 10), t he length of the non-LC block was varied (DPn approximate to 2-25), ac cording to the chosen feed conditions. An X-ray investigation proved t hat polymers 1 gave rise to a sequence of ordered smectic (F or I), sm ectic C, and nematic mesophases with increasing temperature. Their tra nsition temperatures and entropies followed slightly different molar m ass dependences, but each of them reached a saturation value at M(n) a pproximate to 6000 g mol(-1). The same basic mesophase polymorphism wa s also observed for the LC block copolymers 2 and 3, thus suggesting t hat the chemically different blocks were microphase separated within t he solid and LC phases.