(708d) Influence of Polymerizable Organoclays On Thiol-Acrylate Photopoltmerization System

Photopolymerizable organoclays in producing clay nanocomposites can react with monomers and incorporate into polymer matrices during the UV curing process. This research investigates the effects of polymerizable organoclays on the reaction behavior as well as ultimate composite properties based on in-situ thiol-ene photopolymerization. To this end, different types of polymerizable organoclays prepared by changing the functional group structure were examined in various thiol-acrylate systems. Higher chemical compatibility of components induced enhanced clay exfoliation resulting in significant increase in both photopolymerization rate and overall toughness of ultimate nanocomposites compared to those with non-reactive organoclays. In addition, by affecting the stoichiometric ratio of functional groups in the clay gallery, thiolated organoclays facilitate great degree of step-growth thiol-ene reaction with higher thiol conversion while acrylated organoclays encourage acrylate homopolymerization. The enhanced thiol-ene reaction by adding thiolated organoclays also induces less oxygen inhibition with increased flexibility of nanocomposites. Finally, based on increased interaction with polymer networks during the photopolymerization, all types of polymerizable organoclays significantly reduce the polymerization shrinkage and shrinkage stress compared to non-reactive organoclays.