Study of poly(methyl methacrylate) stereocomplexes by size exclusion chromatography and dynamic light scattering

Poly(methyl methacrylate) stereocomplexes prepared in dilute tetrahydrofura n solutions were studied by size exclusion chromatography coupled with refr active index and light scattering detectors in combination with dynamic lig ht scattering. In addition to the molecular/particle weight of the separate d fraction and distribution of radius of the "viscosity" hydrodynamic spher e, the distribution of hydrodynamic radii was obtained as well. By mixing o f iso- and syndiotactic polymers, a considerable increase in polymer partic le mass was observed, while particle size varied much less. Consequently, a n appreciable increase in the segment density of the particles was proved t o be the result of stereocomplexation. This phenomenon was quantified by va riation of the hydrodynamic shrinking factor (ratio of the "viscosity" radi us of the complex particle and free poly(methyl methacrylate) molecule) dur ing the separation. The results obtained support the picture of the stereoc omplex particle as a structure with associated segments of different stereo regularity which should form branched, multifunctional points.