Optical rotatory dispersion studies of poly(l‐α‐methylbenzyl methacrylate) and poly(menthyl methacrylate) in solution

Abstract

AbstractOptical rotatory dispersion studies were carried out on solutions of poly(l‐α‐methylbenzyl methacrylate) and poly (l‐menthyl methacrylate) samples of varying tacticity. Monomeric analogues α‐methylbenzyl pivalate and menthyl pivalate were also investigated in the same way. Ultraviolet spectra of the α‐methylbenzyl series were obtained.The general shape and form of the optical rotation spectra were similar for the several α‐methylbenzyl polymer samples and monomer analogue. The isotactic polymer showed generally higher optical activity than both the syndiotactic and atactic polymers and the monomeric analogue. This was found to be true in several solvent systems. The ratio of the optical activity of the polymer to that of the monomer increased uniformly with decreasing wave length. The temperature dependence of optical activity was small. The ultraviolet spectra of polymeric and monomeric species were very much the same down to the lowest wave lengths measured, of the order of 210 mμ.The menthyl polymers and monomer analogue also showed optical rotation spectra which were similar to each other. For this material all polymers had higher optical activity than the monomeric analogue, but in contrast to that which was found for the α‐methylbenzyl systems, the syndiotactic and atactic polymers showed higher optical rotation than the isotactic material.The relationship of the optical activity of the polymers in solution to the specific conformational structure present is obscured partly by solvent interaction and partly by the fact that the effects of polymer structure on optical activity are small since the asymmetric carbon or carbon atoms are connected by several intermediate bonds to the skeletal backbone of the molecule. The importance of the excited states of the important chromophoric groups of the polymer molecule on the optical activity is discussed.