Polymerization of methacrylate resins photoinitiated by camphorquinone and bulky amine-functionalized silsesquioxanes
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Polyhedral oligomeric silsesquioxanes (SSQO) functionalized with bulky amino groups were prepared by a two-stage synthesis procedure. In a first stage, a modified organotrimethoxysilane was synthesized by reacting 1 mol of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane with 3 mol of 1,2-epoxy-3-phenoxypropane. The second stage consisted of the hydrolytic condensation of the modified silane catalyzed by formic acid. Methacrylate resins were activated for visible light polymerization by the addition of camphorquinone (CQ) in combination with different mass fractions of SSQO. The progress of monomer conversion versus irradiation time showed that the CQ/SSQO pair is an efficient photoinitiator system because a fast reaction and high conversion results from 60 s irradiation at 600 mW/cm2. The SSQO were incorporated up to 22 wt% in the methacrylate resin without compromising the flexural or the compressive properties of the final material.
KeywordsPhotopolymerization Flexural Modulus Compressive Property Photolysis Product Polyhedral Oligomeric Silsesquioxanes
The financial support provided by the CONICET and the ANPCyT is gratefully acknowledged. The authors are grateful to Esstech for the generous donation of the Bis-GMA monomer used in this study.
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