Controlled formation of microheterogeneous polymer networks: Influence of monomer reactivity on gel structure

The mechanistic pathway taken in constructing a three-dimensional polymer n etwork was greatly influenced by the reactivity and the functionality of th e monomers and cross-linkers used. An increase in the cross-linker reactivi ty and functionality were found to promote properties in the polymer networ k that are consistent with a microgel type polymer structure. The microstru cture of polyacrylamide (PAAm) gels synthesized from acrylamide (AAm) with a variety of cross-linkers was investigated using temperature profiles and polymerization rates, electrophoresis, scanning electron microscopy, and cl arity tests. It was discovered that the heterogeneity of these polymers is largely due to the increased reactivity of the cross-linkers and ultimately responsible for improved properties of PAAm gels such as optical clarity a nd enhancement of electrophoretic separation.