Photopolymerization of a novel tetraoxaspiroundecane and silicon‐containing oxiranes

Abstract

Abstract New multifunctional silorane‐based systems were investigated, with respect to their photoreactivity, as potential matrix resins for low‐shrinkage/stress dental composites. The objective of this investigation was to synthesize and evaluate the reactivity of a silicon‐analogue oxaspirocyclic monomer with silorane‐based matrix resin systems during visible‐light polymerization. The experimental formulations contained (1) a silicon‐containing 1,5,7,11‐tetraoxaspiro[5.5]undecane (TOSU– IV ), (2) a phenylmethylsilane containing two cyclohexyloxiranyl groups, (3) a cyclotetrasiloxane containing four cyclohexyloxiranyl groups, and (4) a photocationic initiator system. Three main aspects were studied: (1) the photoreactivity of the tetraoxaspiroundecane (TOSU)/silorane reactant mixtures with differential scanning photocalorimetry, (2) oxirane ring‐opening reactions of siloranes during binary photopolymerization with Fourier transform infrared (FTIR), and (3) oxaspirocyclic ring‐opening reactions of the TOSU reactant during homophotopolymerization and binary photopolymerization with FTIR and NMR. A diallyl ether precursor of TOSU– IV was also included in selected studies. The main findings were as follows: (1) a feasible route for the successful synthesis of a silicon analogue (TOSU– IV ) was developed; (2) TOSU– IV was compatible and photoreactive, making possible the reduction of polymerization stress in silorane‐based matrix resins; and (3) spectroscopic evidence for both oxirane and oxaspirocyclic ring opening during the visible‐light photopolymerization of the test formulations was found. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 336–344, 2007