Study on dipole moments of macromolecules, 3. Dipole moments of poly(4‐methoxystyrene) and poly(4‐bromostyrene) and their dependences on solvent and temperature
1991; Wiley; Volume: 192; Issue: 3 Linguagem: Inglês
10.1002/macp.1991.021920306
ISSN0025-116X
AutoresMikiko Shima, Noriko Yamaguchi, Mari Sato,
Tópico(s)Inorganic and Organometallic Chemistry
ResumoAbstract 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°C. The average dipole moments per constitutional repeating unit (μ) obtained in benzene (Bz), 1,4‐dioxane (Dox), and toluene (Tol) at 25°C are as follows: 1,219 D (Bz), 1,253 D (Dox) and 1,175 D (Tol) for PMeOSt, and 1,371 D (Bz) and 1,413 D (Dox) for PBrSt In SI units: 1 D ≈ 3,33564 · 10 −30 C · m. . The dipole moment ratio, D r = 〈μ 2 〉 2 /μ 2 0 , was found to be 0,942 for PMeOSt and 0,467 for PBrSt in Bz at 25°C, for which the observed values of the dipole moments of 4‐methoxytoluene and 4‐bromoethylbenzene were used as μ 0 for the respective polymer. The variation of the dipole moment ratio with temperature was linear but very small, d D r /d T giving a negative value for PMeOSt but a positive value for PBrSt.
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