CHIRAL METHACRYLIC POLYMERS CONTAINING PERMANENT DIPOLE AZOBENZENE CHROMOPHORES - SYNTHESIS AND CHARACTERIZATION

xyethyl)-N-(2-methylbutyl)]amino-4'-cyanazobenzene (MBAC), a new optic ally active photochromic monomer having a large permanent dipole momen t was prepared in six steps starting from (S)-2-methyl-1-butanol. Home - and copolymerization of MBAC with butyl methacrylate was carried out in benzene at 70 degrees C in the presence of AIBN as a radical initi ator. The polymeric materials, having a molar content of MBAC units be tween 21 and 100%, were characterized by an almost random distribution of monomeric units and a glass transition temperature ranging from 70 to 110 degrees C. 2D COSY analysis allowed to attribute all signals o f their rather complex H-1 NMR spectra and to suggest that intramolecu lar charge transfer mesomers significantly contribute to the electroni c distribution of the azobenzene chromophore. Asymmetric perturbation of the azobenzene chromophore, that could be at least partially attrib uted to the presence of short-order segments along the polymer chain, was evidenced by circular dichroism.