Polyelectrolyte Networks Based on Poly(Para-phenylene)s: Synthesis, Preparation of Thin Films, and Swelling Behavior

The preparation of poly(para-phenylene) (PPP) derivatives with sulfonate groups and photo cross-linkable side chains is described. These statistical copolymers are used to construct molecularly reinforced polyelectrolyte networks. Their swelling behavior as thin films with covalent attachment to a solid substrate is investigated by multiangle null-ellipsometry in a total internal reflection geometry (TIRE). Different mixtures of water, tetrahydrofurane, and added sodium chloride as well as a variation of the network structure show that the behavior of the networks is mainly determined by the balance of hydrophobic and hydrophilic groups of the polyelectrolyte. Increasing degree of swelling on addition of salt to water/THF mixtures suggests a preferential solvation of the organic compound in the network.