Studies on Polyelectrolyte Solutions VII. Fast, Heterogeneous, and Slow Diffusion Modes of Poly(diallyl-N,N-dimethylammonium chloride) in Aqueous Alcoholic Salt Solvents

摘要: Dynamic light scattering measurements were performed on aqueous alcoholic salt solutions of poly(diallyl-N,N-dimethylammonium chloride) (PDADMAC, Mw=2.5×105 g mol−1) in the semidilute regime, where salts used NaCl and Na2SO4. The results indicate existence three diffusive processes, a fast, heterogeneous, slow mode. fast diffusion mode, Dfast, is interpreted as coupled motion polyion blob with its surrounding small ions. Such contains average segments which are connected to give linear coil behaves if it isolated dilute solution. Experimentally, found that increases increasing concentration content. This indicates electrostatic segment-segment interactions become more screened poorer solvent quality is. Dslow, refers large clusters, having an internal ordered structure. These clusters can be 300 nm or more. They stabilized by intermolecular destroyed strong hydrophobic interactions, when degree dissociation converges versus zero, so polyions neutral. At this limit Dslow disappears may equal Dcop, cooperative coefficient solution neutral polymers. heterogeneous Dhetero, caused parts chains not incorporated into cluster domains. Their total usually rather observation often difficult. one extreme, such part blob. Then there no we have Dhetero=Dfast. other Dhetero describe complete single chain whose dimensions domain becomes Dslow. As consequence, while Dfast nearly always present, lie too near respectively, separation impossible. simultaneous detection all modes possible only using multiple tau technique. With old correlators conventional analysis methods decomposition very difficult Mostly finds two modes, has lead erroneous idea, extraordinary-ordinary phase splitting. In reality, however, splitting transition. All present simultaneously technical problem their resolution.