Study on Dipole Moments of Macromolecules II. Dipole Moments of p-Methoxytoluene, p-Bromoethylbenzene and p-Bromotoluene as Structural Units of Poly(p-methoxystyrene) and Poly(p-bromostyrene)

Abstract

ABSTRACT:The dipole moments of p-methoxytoluene (p-MeOTol), p-bromoethylbenzene (p-BrEtBz), and p-bromotoluene (p-BrTol) corresponding to structural units of poly(pmethoxystyrene) and poly(p-bromostyrene) were determined from dielectric constant and density measurements on their benzene, p-dioxane, and toluene solutions over the temperature range of 25-55°C, and we examined the effects of solvent and temperature on the dipole moments. In the preceding paper, 1 we reported the dielectric measurements of organic solvents, and poly(p-methoxystyrene) in solution, introducing a new apparatus consisting of capacitance bridge and a three-terminal platinum electrodes cell. The dielectric constants obtained using the new apparatus were accurate and the accuracy of the dipole moment was improved by one more order than that obtained before. 2 • 3 of the polymer chain with x bond dipoles in magnitude Jlo in the chain and is the mean square end-to-end distance of the unperturbed chain with n bonds of length /, and an important parameter often used in conformational analysis of polymer chains.The mean square dipole moment of polymer is a configuration-dependent property of the polymer chain when the polymer has polar groups in each structural unit. The dipole moment ratio, given by the equation Dr= is an analogue of the characteristic ratio, Cr= of the chain dimension, where (m 2 ) is the mean square dipole moment A number of experimental results of the dipole moments of polymers determined in various solvents and temperatures have been reported but in the estimation of Dr, a fixed value of Jlo has generally been used, assuming that solvent and temperature have little effect on the value of Jlo· However, as an earlier study 4 showed, the dipole moments of organic compounds, such as chlorobenzene, nitrobenzene, and ethyl ether were sensitive to the solvent in which the measurements were performed, and theoretical studies of solvent 735

Dipole Moment of Poly(ethylene oxide) in Solution and Its Dependence on Molecular Weight and Temperature

“…Taking the value of DE ¼ 1:20 D, a dipole moment ratio of PEO in benzene h 2 i= DE 2 of 0.746 at 25 C is obtained, which is a factor that is dependent on the degree of flexibility in the polymeric chains. In previous studies, 20,21…”