PREPARATION AND CHARACTERIZATION OF CYCLOPOLYMERIZABLE RESIN FORMULATIONS

An amine-catalyzed reaction between acrylates and formaldehyde has bee n used to convert mono-acrylates to difunctional monomers and di-acryl ates to multifunctional oligomers by linking the acrylic double bonds together in 1,6-diene pairs. The resulting monomers and oligomers unde rgo efficient cyclopolymerization to high conversion with significantl y less shrinkage than normally found for acrylates. In this study, a c onvenient single-step process was used with mixtures of mono- and di-a crylate starting materials to produce a series of resins with potentia l for effective cyclopolymerization. Incremental changes in the ethyl acrylate (EA) to ethoxylated bisphenol A diacrylate (EBPAD) ratio dire ctly supplied cyclopolymerizable resins with a broad range of viscosit ies and product distributions. Those resins produced from reaction mix tures rich in EA have low viscosities because of high diluent monomer contents and limited oligomerization of EBPAD due to end-cap formation . Resin viscosity and average molecular weight of the oligomeric compo nent of the resin were inversely related to the amount of EA used in t he reaction. Through the choice of reactants and their ratio, this sim ple technique has the potential to provide cyclopolymerizable resins f or use in a variety of dental polymer applications.