Conformation of poly(dimethyl siloxane) and polystyrene in solution measured by polarized Raman scattering

• Published in: Journal of polymer science. Polymer physics edition 1975-05, Vol.13 (5), p.997-1009
• Main Authors: Speak, R., Shepherd, I. W.
• Format: Article
• Language: English
• ISSN: 0098-1273; 1542-9385
• DOI: 10.1002/pol.1975.180130512

Depolarization ratios ρ have been measured over ranges of temperature T and molecular weight M for polystyrene (PS) dissolved in cyclohexane (1002 cm −1 Raman band) and for poly(dimethyl siloxane) (PDMS) dissolved in benzene (2907 cm −1 Raman band). The ranges in the case of PS are 15 < T < 65°C and 2 × 10 3 < M < 4 × 10 5 and in the case of PDMS are −3 < T < 60°C and M = 10 4 . Measurements were also made of PDMS radii of gyration using conventional light scattering. The results are interpreted in terms of a theory connecting rotational isomeric populations with polymer extension. In the case of PDMS, an experimental value of the proportionality constant for trans isomers ( D 2 = −3.9 ± 0.9) is deduced. This is closer to the theoretical value than previous estimates but there is still some discrepancy. In the case of PS the isomeric changes resulting from extension are independent of M for M > 10 4 . Deviations are observed for lower M .