COPOLYMERIZATION OF CHIRAL AND CHROMOPHORIC COMONOMERS - A PATHWAY TOOPTICALLY-ACTIVE FUNCTIONAL POLYMERS

The extension of the copolymerization method, first proposed by the au thors, to the preparation of functional optically active polymeric mat erials is discussed. In the case of copolymers between chiral monomers in a pure enantiomeric form and comonomers containing photosensitive chromophores, the electronic transitions of the aromatic chromophore s how dichroic bands thus allowing to correlate chiroptical properties w ith photophysical and photochemical behaviour. The type of correlation is dependent on comonomer structure and copolymer microstructure (seq uence distribution and stereoregularity). The examples discussed mainl y concern acrylic and methacrylic photochromic monomers and the acryla te, methacrylate and vinyl ether of (-)-menthol as optically active pa rtners. Also acrylic and methacrylic derivatives are reported as suita ble monomers for preparing cholesteric and chirally twisted liquid-cry stalline polymers. In these copolymers between an optically active mes ogenic monomer with an achiral mesogenic comonomer, helical structures associated with the asymmetric interactions between chiral and achira l side chains are obtained. The examples discussed provide clear evide nce of the versatility of the copolymerization method for preparing po lymeric materials capable of giving chiral dynamic responses and displ aying properties related to their chiral structures.