Photopolymerization of a novel tetraoxaspiroundecane and silicon‐containing oxiranes

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.

Temperature Changes in Silorane‐, Ormocer‐, and Dimethacrylate‐Based Composites and Pulp Chamber Roof during Light‐Curing

“…The temperature curve observed in the present study implied that the cationic ring‐opening of Filtek LS has the so‐called frontal behavior, with the polymerization front of silorane functional monomers showing a very steep temperature profile 15 . The rapid rise in the heat that evolved up to a maximum followed by a slower rate of decline may be associated with an increased rate of “diffusion‐controlled termination reactions and reduced mobility of growing polymer chains.” 17 …”

Patient‐reported outcome measures suitable to assessment of patient navigation

“…The resin is a mixture of the diepoxides bis[2‐(7‐oxabicyclo[4.1.0]hept‐3‐yl)ethyl]methylphenylsilane 1 (BECEPSi, Scheme ) and the tetrafunctional cyclosiloxane epoxide 2,4,6,8‐tetrakis[2‐(7‐oxabicyclo[4.1.0]hept‐3‐yl)ethyl]‐2,4,6,8‐tetramethyl‐1,3,5,7‐tetraoxa‐2,4,6,8‐tetrasilacyclooctane (TECTMSi). In addition, it was found that the spiro monomer 3,9‐diethyl‐3,9‐bis(trimethylsilylpropoxymethyl)‐1,5,7,11‐tetraoxaspiro[5.5]undecane (TOSU) may significantly reduce the polymerization stress of these epoxide mixture 104–107. For the main monomer TECTMSi, the term “silorane” was introduced to represent hybrid monomer systems that contain both siloxane and oxirane structural units.…”

Visible‐Light Initiated Free‐Radical/Cationic Ring‐Opening Hybrid Photopolymerization of Methacrylate/Epoxy: Polymerization Kinetics, Crosslinking Structure, and Dynamic Mechanical Properties

“…The acrylates, which undergo free‐radical polymerization, exhibit high reaction rates and offer a large selection of monomers and initiators. The epoxides and vinyl ethers, which undergo cationic polymerization, do not suffer from oxygen inhibition and exhibit low toxicity and shrinkage …”