Structure and viscosity of spherical polyelectrolyte microgels: A model for the polyelectrolye effect?

摘要: Spherical microgels made of polystyrene sulfonic acid can be regarded as slightly swollen polyelectrolyte “balls” that cannot change their conformation due to the inner cross-linking. Because theory-compatible shape (spherical), practical absence intramolecular effects and van der Waals interactions, they are ideal models examine benchmark theories. In salt-free aqueous solution, both static structure factor solution viscosity analyzed in terms dependencies on concentration, typical behavior is observed, i.e., a steep increase reduced specific with decreasing concentration well formation ordered structures. A more complete picture provided by systematic examination macroions over one decade radii (5nm < R 70 nm). This mesoscopic range molecular mass covers gap between linear polyelectrolytes classical latex spheres . Solution structuring, phase separation theconcentration dependence interparticle distances show importance electrostatic attractive forces. confirmed salt cross-linking-density dependent experiments. Scattering data also refmed version Coulomb potential/MSA within primitive model existence effective repulsive The curves described modemode coupling approximation introduced Hess Klein. formalism allows recalculation from light scattering curves, resulting quantitative agreement measured calculated values. Finally, transferred high precision measurements same chemical composition, where direct comparison expected reveal It seen predominant effect still intermolecular nature, i.e. interaction potential, but an chain stretching identified. pronounced for small polymers than large polymers.