Keynote Address: Intentionally Designed Heterogeneous Polymers: Control of Structure and Properties

Most dental restorative polymers are formed as compositionally homogeneous networks derived from dimethacrylate monomer mixtures.  By selecting monomers that display marginal thermodynamic mixing compatibilities, well-controlled heterogeneous polymer structures can be generated by phase separation induced early in the polymerization process and then locked in place by continued network development.  With this approach, the properties of each phase and their sequence of development can be dictated such that physical, in addition to chemical, aspects of polymer formation are involved.  This provides a means to favorably alter polymer properties such as shrinkage, stress and strength.  Other methods that include addition of linear or nanogel prepolymers to resins as well as the application of polymeric surface treatments to composite fillers have been examined as alternate routes to heterogeneous dental materials with low polymerization shrinkage and stress.  Photo-active prepolymers that generate spatially localized initial polymerization with enhanced stress reduction potential will also be detailed.