DYNAMIC LIGHT-SCATTERING AND PULSED GRADIENT SPIN-ECHO NMR MEASUREMENTS OF DIFFUSION IN POLYSTYRENE POLY(VINYL METHYL-ETHER) TOLUENE SOLUTIONS

The results of dynamic light scattering (DLS) and pulsed gradient spin-echo (PGSE) NMR measurements on ternary solutions of poly(vinyl methyl ether) (PVME) and polystyrene (PS) in toluene are presented. Samples with four different values (0.001, 0.056, 0.114, and 0.246) of x, the ratio of PS concentration to the total polymer concentration, were studied. The total polymer concentration C was varied between approximately 70 and 500 kg m-3 for each value of x. The molar masses of the PVME and PS were 110 000 g mol-1, and the measurement temperature was T = 30-degrees-C. DLS experiments were performed on the samples with x = 0.056, 0.114, and 0.246. The DLS experiments on these samples gave a single mode of decay from which a diffusion coefficient was extracted. PGSE experiments were performed on all of the samples. The PS self-diffusion coefficient was obtained from PGSE experiments on the x = 0.056, 0.114, and 0.246 sets of samples, and the self-diffusion coefficient of the PVME was obtained from measurements on the x = 0.001 samples. The diffusion coefficients obtained from the DLS experiments were found to be equal within experimental errors to the PS self-diffusion coefficients obtained from PGSE NMR experiments on the same samples. The DLS diffusion coefficient did not vary measurably with x at a given value of C for the molar masses and concentrations studied here.