The synthesis and characterization of a liquidcrystalline triblock copolymer containing ethoxycarbonylazobenzene units were described.The methacrylate containing ethoxycarbonylazobenzene functional group

6-(4-(4-ethoxycarbonylphenylazo)phenoxy)hexyl mathacrylate (C6ET)

was prepared as the monomer.For the synthesis of the triblock copolymer

a macro-initiator was prepared by the reaction of PEO2000 with an excessive amount of 2-bromoisobutyryl bromide catalyzed with triethylamine.The ABA triblock copolymer (PC6ET-PEO-PC6ET) was obtained by ATRP of C6ET with the macroinitiator.For comparison

a homopolymer PC6ET also was obtained by the atom transfer radical polymerization (ATRP) of C6ET.UV-Vis spectroscopy

FT-IR spectroscopy

1H-NMR analysis and GPC measurements were used to characterize the structure and molecular weights of the products.Thermal analysis

optical microscopy and X-ray diffraction were used to characterize the LC phase types and phasetransition temperature.Results show that PC6ET is a liquid crystalline polymer with smectic phase.The clearing temperature of the homopolymer was 20℃ higher than the corresponding azo polymer with alkoxyl groups

which indicated the effect of substitutents on the liquid crystalline properties.The cleaning temperature of the ABA triblock copolymer PC6ET-PEO-PC6ET was slightly lower than that of the homopolymer.The phase transition temperatures of the homopolymer and block copolymer were determined to be Cr 70 s 153 i 151 s 58 g

and Cr 65 s 139 i 139 s 48 g (℃) respectively.The azobenzene-containing block copolymer could be used as a potential photoinduced self-assemble system.