Laser light scattering of the molecular weight distribution of unfractionated phenolphthalein poly(aryl ether sulfone)

Two unfractionated samples of phenolphthalein poly(aryl ether sulfone) (PES-C) were characterized in CHCl₃ at 25°C by applying a recently developed laser light-scattering (LLS) procedure. The Laplace inversion of precisely measured intensity–intensity time correlation function lead us first to an estimate of the characteristic line-width distribution G(Λ) and then to the translational diffusion coefficient distribution G(D). A combination of static and dynamic LLS results enabled us to determine D = (2.69 × 10^?4)M^?0.553, which agrees with the calibration of D = (2.45 × 10^?4)M^?0.55 previously established by a set of narrowly distributed PES-C samples. Using this newly obtained scaling between D and M, we were able to convert G(D) into a differential weight distribution f_w(M) for the two PES-C samples. The weight-average molecular weights calculated from f_w(M) are comparable to that obtained directly from static LLS. Our results showed that using two broadly distributed samples instead of a set of narrowly distributed samples have provided not only similar final results, but also a more practical method for the PES-C characterization. © 1997 John Wiley & Sons, Inc.