Determination of the optical anisotropy of atactic polystyrene using a grating monochromator

✍ Scribed by Nádya Pesce da Silveira; Dimitrios Samios; Frank Strehle; Thomas Dorfmüller

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 653 KB
• Volume: 197
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1996.021970614

✦ Synopsis

Abstract

To extract the intrinsic molecular scattering from unwanted collision‐induced contributions as much as possible we propose a simple useful method recording the depolarized Rayleigh spectra using a double grating monochromator and correcting the spectra for the high‐frequency wings. For this purpose we tested the system polystyrene/CCl~4~ for which an asymptotic value of the optical anisotropy 〈γ^2^〉/x ≅ 30 Å^6^ with degree of polymerization x > 20 was found. The depolarized Rayleigh intensity of 2,4‐diphenylpentane and anionically polymerized atactic polystyrene standards was also measured in dilute solutions in the θ‐solvent bicyclohexyl (θ = 61°C). From the absolute depolarized Rayleigh ratio we obtained the configurational average optical anisotropy per number of monomer units, 〈γ^2^〉/x. We have chosen cumene as a model compound estimating that its optical anisotropy is similar to that of a quasi monomer unit. No significant temperature dependence of 〈γ^2^〉/x and of the static internal pair correlation in the temperature range from 25°C up to 80°C was found.