Depolarized Rayleigh scattering and orientational motion of polyethylene glycol

The depolarized Rayleigh light scattering spectra of pure polyethylene glycols and their solutions in an optically isotropic solvent were studied as a function of polymer molecular weight, concentration, and temperature. Reorientational relaxation times were obtained by fitting the observed spectra to Lorentzian functions convoluted with the experimental spectrum. The relaxation times were found to increase with increasing molecular weight and with dilution. The depolarized Rayleigh results for the polyethylene glycols were compared with results for other polymer systems and with results obtained using other types of relaxation studies. By studying the dependence of the relaxation times on viscosity, temperature, and concentration and comparing the results with theoretical predictions of molecular and end-group reorientations, we have associated the depolarized Rayleigh spectra of polyethylene glycol with rotation of the entire polymer molecule.