Two kinds of novel oxetane monomers, containing biphenyl, flexible spacer and cinnarnoyl group, were synthesized. The liquid crystal phase behavior of the corresponding polymers was investigated and isotropic-nematic, nematic-smectic and smectic-crystal transitions were identified during cooling. Both polymers exhibited clear fan texture morphology under a polarized optical microscope. Irradiation of a polymer film with linearly polarized UV light led to cycloaddition of the cinnamoyl groups, causing simultaneous alignment of the liquid crystal unit. (c) 2006 Elsevier B.V. All rights reserved.