SOLUTION PROPERTIES AND DYNAMIC BULK BEHAVIOR OF INTRAMOLECULAR CROSS-LINKED POLYSTYRENE

Linear polystyrene (PS) molecules were intramolecularly cross-linked with p-bis(chloromethyl)benzene in dilute solution. The resulting 'microgels' were characterized in solution by static and dynamic light scattering, GPC, and viscosity measurements. We find a surprisingly small reduction of the radius of gyration and the hydrodynamic radius even for highly cross-linked PS molecules having molecular weights up to 5 multiplied by 10**5 and an average number of P//c equals 20 monomer units between cross-links. Dynamic mechanical measurements in samples having P//c greater than equivalent to 10 yield no change of the plateau modulus in comparison to the linear molecules but a broadening and shift to lower frequencies of the terminal zone if compared with linear PS. Furthermore, we find that the product of the self-diffusion coefficient and the zero-shear viscosity is constant, and the diffusion of PS chains in a matrix of microgels is independent of the cross-link density. Various explanations are discussed, but no decision for a particular model (describing all experimental results) can be made.