MORPHOLOGICAL-STUDY OF A CHIRAL POLYMER NETWORK IN A NEMATIC LIQUID-CRYSTAL FROM A CONCENTRATION GRADIENT

A contact preparation is made between a cholesteric photocrosslinkable material and a standard nematic liquid crystal. The concentration and the anisotropy progressively and homogeneously vary along a direction perpendicular to the diffusion front. On the basis of scanning electr on microscopy investigations, comparisons are made between the modific ations of the polymer network from a sample region rich in one compone nt to the complementary region rich in the other. Such a preparation o ffers the opportunity to visualize the morphological transformations w hen a phase transition occurs and the morphologies intrinsic to textur es intermediate between well-classified mesomorphic textures. Scanning electron microscopy texture observations are made in parallel with th ose by optical microscopy in order to make the connection with the mes omorphic textures, which therefore act as indicators during the subseq uent SEM investigations.