STUDY ON DIPOLE-MOMENTS OF MACROMOLECULES .3. DIPOLE-MOMENTS OF POLY(4-METHOXYSTYRENE) AND POLY(4-BROMOSTYRENE) AND THEIR DEPENDENCES ON SOLVENT AND TEMPERATURE

Dipole moments of poly(4-methoxystyrene) (PMeOSt) and poly(4-bromostyrene) (PBrSt) were determined from dielectric constant and density measurements on dilute solutions of the polymers in benzene, 1,4-dioxane and toluene, over the range of temperatures from 25 to 55-degrees-C. The average dipole moments per constitutional repeating unit (mu) obtained in benzene (Bz), 1,4-dioxane (Dox), and toluene (Tol) at 25-degrees-C are as follows: 1,253 D (Dox) and 1,175 D (Tol) for PMeOSt, and 1,371 D (Bz) and 1,413 D (Dox) for PBrSt(b). The dipole moment ratio, D(r) = [mu-2]/mu-0(2), was found to be 0,942 for PMeOSt and 0,467 for PBrSt in Bz at 25-degrees-C, for which the observed values of the dipole moments of 4-methoxytoluene and 4-methoxytoluene and 4-bromoethylbenzene were used as mu-0 for the respective polymer. The variation of the dipole moment ratio with temperature was linear but very small, dD(r)/dT giving a negative value for PMeOS but a positive value for PBrSt.