Preparation and Characterization of Crosslinked Liquid-Crystalline Polymer Films with a Long Spacer

Abstract

Three azobenzene acrylate monomers containing alkyl spacers of different length were synthesized. Thermodynamic and mesomorphic properties of the monomers were measured by differential scanning calorimetry and polarizing optical microscopy. A crosslinker with the undecyl spacer was also synthesized to prepare crosslinked liquid-crystalline polymer films by photopolymerization. Polarized UV spectra and polarizing optical micrographs demonstrated that the mesogens are aligned homogeneously in the films. Low glass transition temperature of the films enabled them to bend near room temperature upon UV irradiation. Besides, the films generally bent away from the light source before they at last bent towards the light irradiation.

Keywords:

• crosslinked liquid-crystalline polymer film
• long spacer
• photoinduced bending

Acknowledgments

Financial supports from National Natural Science Foundation of China (No. 20404001), Shuguang Plan of Shanghai Education Development Foundation (05SG07), and Shanghai “Phosphor” Science Foundation (06QA14009) are gratefully acknowledged.

Notes

^a K, crystal; S, smectic; N, nematic; I, isotropic.