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Abstract
This paper reports on the phase behaviour of photochemically polymerized 2-hydroxyethyl methacrylate in a nematic liquid crystalline solvent. Samples were prepared via polymerization by ultraviolet (UV) radiation of initial solutions made of the reactive monomer 2-hydroxyethylmethacrylate (HEMA) and a photoinitiator (Darocur 1173). The swelling and deswelling properties were studied by polarized optical microscopy in a wide range of temperature for the low molecular weight liquid crystal 4-cyano-4′-pentylbiphenyl (5CB). Immersion of polymerized HEMA in an excess of 5CB did not exhibit any significant change of sample size and showed only limited dependence on temperature, indicating strong polymer/liquid crystal interactions.
Polymer/liquid crystal films were prepared by polymerization-induced phase separation of HEMA/Darocur 1173/5CB blends using UV radiation. The electro-optical behaviour of the films obtained was investigated as function of the initial composition and applied voltage. Strong memory effects have been observed in the case of samples prepared from 60 weight% 5CB/40 weight% HEMA.
Acknowledgments
The authors gratefully acknowledge financial support from Algerian and French governments allowing the stay of the first author (F.Z. Elouali) at the laboratory of Lille.
