Preparation and Characterization of Cyclopolymerizable Resin Formulations

Abstract

An amine-catalyzed reaction between acrylates and formaldehyde has been used to convert mono-acrylates to difunctional monomers and di-acrylates to multifunctional oligomers by linking the acrylic double bonds together in 1,6-diene pairs. The resulting monomers and oligomers undergo efficient cyclopolymerization to high conversion with significantly less shrinkage than normally found for acrylates. In this study, a convenient single-step process was used with mixtures of mono- and di-acrylate starting materials to produce a series of resins with potential for effective cyclopolymerization. Incremental changes in the ethyl acrylate (EA) to ethoxylated bisphenol A diacrylate (EBPAD) ratio directly supplied cyclopolymerizable resins with a broad range of viscosities and product distributions. Those resins produced from reaction mixtures 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 component of the resin were inversely related to the amount of EA used in the reaction. Through the choice of reactants and their ratio, this simple technique has the potential to provide cyclopolymerizable resins for use in a variety of dental polymer applications.

Polyisobutene/polycyclohexyl methacrylate interpenetrating polymer networks

“…The rates of network formation were followed in the bulk, in real time, in the near and middle infrared (NIR and MIR) regions (7500e1800 cm À1 ) using a Bruker spectrometer (Equinox 55). The PCHMA and PIB network formations were followed by monitoring the disappearance of the HeC]C overtone absorption bands at 6167 cm À1 [15] and of the isocyanate functions at 2270 cm À1 [16], respectively, as described previously [5]. Each peak area was directly proportional to the reagent concentration (the BeereLambert law has been verified), thus the conversionetime profile was derived easily from the spectra recorded as a function of time.…”

Photo-polymerisation of composite resins measured by micro-Raman spectroscopy

“…They are listed in Table 1. The bands at 1608 and 1583 cm 21 [11] are associated with the aromatic CyC stretching vibrations and can be used as internal standards. Another band, centred around 1576 cm 21 (see Fig.…”

Analysis of residual stress in the resin of metal-resin adhesion structures by scanning acoustic microscopy

“…Such expanding monomers have been synthesized [21][22] , but they can not be used in dental applications. For polymerization shrinkage to be minimized, the resin must have monomer components which will all efficiently engage in cyclopolymerization processes while maintaining an adequate crosslink density in the resulting polymer, however there is yet no remarkable achievement at present 23) .…”