Liquid crystal acrylate-based networks: polymer backbone-LC order interaction

New synthetic pathways to poly- and monodomain acrylate-based networks via gamma-irradiation and chemical crosslinking are described. Strain-induced o rientation transitions and phase behavior are studied by X-ray scattering, differential scanning calorimetry and optical microscopy. Analysis of the o bserved phenomena is given in terms of crosslinking conditions, network top ology, structure and spatial distribution of crosslinks. The pretransitiona l behavior and the observed shifts in clearing point Tn-i are in good agree ment with theoretical predictions. The reorientation process in monodomain networks is regulated via strain gradients generated by external mechanical field. The variation in geometrical shape of the samples gives an opportun ity to control and realize two different reorientation mechanisms: uniform director rotation and reorientation via stripe domains. Gamma-irradiation i s found to be a powerful tool for fixation of any current distribution of p oly- and monodomain regions within the LC film. 'Macroscopic memory' of the information recorded on the films is observed and discussed. (C) 1999 Else vier Science BN. All rights reserved.