Monomeric unit distribution and optical activity of copolymers: random copolymers of acrylic acid and N-(s-butyl)- N-methyl acrylamide antipodes

Abstract

For copolymers of acrylic acid and N-(s-butyl)- N-methyl acrylamide antipodes as for most copolymers, the dependence of the optical rotatory power was found to be non-linear with regard to their composition. This non-linearity has been discussed generally in terms of conformation or second-ary structure. It is proposed that this effect is due to the presence of more than two independent optically active species. The different species were found in terms of triads as the effect of neighbours on the partial specific contribution of a monomeric unit to the total optical activity. A relation was developed for a random copolymer with ideal distribution using eight triads. This relation was applied to acrylic acid/(+) and (−) N-(s-butyl)- N-methyl acrylamide copolymers which can be considered as ideally random; good independent agreement of the optical purity was obtained. The results are discussed in terms of induced optical activity at the level of the electronic transitions of achiral acid unit chromophores.