In situ study of photopolymerization of liquid-crystalline acrylates

The photopolymerization of oriented liquid-crystalline (LC) acrylates, including the S-A phase of 4-n-hexyloxyohenyl-4'-acryloyloxyhexyloxybenzoate (M-l) and the chiral S-I* phase of (S)-4-(5-acryloyloxy-4-methylpentanoyloxy)-4'-n-octyloxybiphenyl (M-2), was studied by IR spectroscopy. In the absence of photoinitiator, the UV irradiation of the LC layers was accompanied by virtually complete conversion of monomers, The degree of orientation in polymer film on the basis of M-2 coincides with that in the initial acrylate (0.65), while in the film based on M-l, the degree of orientation is 15% lower than that in the initial monomer. The degree of orientation in polymer films remains unchanged on heating the samples to 60 degrees C. The further heating leads to a sharp drop in the degree of orientation in the temperature intervals corresponding to conformational disordering of the side groups.