New model polyelectrolytes

Poly(styrene sulfonate) (PSS) is probably the most widely studied synthetic polyelectrolyte, since narrow molecular weight distribution products can be made by sulfonation of anionically made polystyrene. Through anionic polymerization flexible PSS chains may be incorporated into well-defined block copolymer and branched homopolymer and copolymer structures. 1,3-Cyclohexadiene is a monomer that is attracting increasing attention from synthetic polymer chemists. Under appropriate conditions, this monomer may also be anionically polymerized, leading to well-defined linear and branched homopolymers and copolymers. The microstructure of the resulting polymer (1,4 versus 1,2 content) may be manipulated through choice of polymerization conditions, with a resulting impact on chain conformation and properties. In addition, the unsaturated nature of poly(cyclohexadiene) (PCHD) allows the properties of these materials to be further manipulated through postpolymerization chemistry. This includes the creation of novel synthetic polyelectrolytes through sulfonation chemistry. In this presentation we describe some of the unique polyelectrolyte architectures that can be made based upon PSS. We will then describe the anionic synthesis and characterization of PCHD and sulfonation of PCHD to yield poly(cyclohexadiene sulfonate) (PCHDS), a new semi-flexible synthetic polyelectrolyte. The effect of various sulfonation conditions on the nature of the product and the extent of sulfonation will be presented, as will the synthesis of PCHDS-based block copolymers. The synthesis of perdeuterated PCHDS, to facilitate neutron scattering studies, will be detailed. Finally, the synthesis and preliminary aqueous gel permeation chromatography characterization of poly(p-phenylene sulfonate), a rigid polyelectrolyte obtained by aromatization of PCHD followed by sulfonation, will be described.