Urethane dimethacrylates with carboxylic groups as potential dental monomers. Synthesis and properties

Abstract

New urethane dimethacrylate oligomers functionalized with carboxylic acid groups (CAd-1-÷4) were synthesized and evaluated as co-monomers in dental resin composites. Photopolymerization of these oligomers containing polyethylene oxide spacer was monitored by FT-IR spectroscopy comparatively with the low molecular monomer (CAd-M), as well as by fluorescence technique. The polymerization shrinkage for several mixtures including the urethane oligomers and BisGMA/ TEGDMA system was determined and, for some cured specimens, the equilibrium water uptake, water sorption and contact angle were measured to establish their behaviour into a wet environment. The compatibility between the organic and inorganic phase was investigated by SEM analysis in fractured surfaces indicating the formation of compact homogeneous materials. Aspects of the crack propagation behaviour of some composites subjected to Vickers indentation were examined by polarizing optical microscopy (POM) and atomic force microscopy (AFM), a visible crack being visible only in AFM image. Mechanical properties (compressive and diametral tensile strengths), determined for several resins composites, sustains the formation of materials with a hardness comparable to those frequently encountered in dental practice. © 2009 The Society of Polymer Science, Japan.