Synthesis and Photopolymerization of Thiol‐Modified Triazine‐Based Monomers and Oligomers for the Use in Thiol‐Ene‐Based Dental Composites

Abstract

Thiol‐ene photopolymerizations combine the unique features of step‐growth reactions and photoinitiated polymerizations, so that they experience a growing interest for applications such as coatings or dental restoratives. Most studies have making use of a relatively flexible ester and the hydrolytically labile derivative pentaerythritoltetra(3‐mercaptopropionate) (PETMP) as the thiol component in common. In this study, the performance of hydrolytically stable 1,3,5‐tris(3‐mercaptopropyl)‐1,3,5‐triazine‐2,4,6‐trione (4a), 1,3,5‐tris(2‐methyl‐3‐mercapto‐propyl)‐1,3,5‐triazine‐2,4,6‐trione (4b), and oligomers thereof in thiol‐ene photopolymerizations is investigated. The oligomers are prepared via thiol‐Michael or thiol‐isocyanate additions by using 4a and suitable diacrylates or diisocyanates containing a rigid core structure. Compared with PETMP, the thiol derivative 4a shows better flexural strength and modulus of elasticity in thiol‐ene photopolymerizations with 1,3,5‐triallyl‐1,3,5‐triazine‐2,4,6‐trione (TATATO) as the‐ene derivative. This phenomenon becomes especially evident after storage in water at 37 °C for 24 h. Furthermore, the performance regarding the flexural strength, the Young's modulus of elasticity, the polymerization shrinkage stress of 4a, and the polyadducts thereof in dental filling composites is evaluated and discussed.

Ester-free thiol–ene dental restoratives—Part A: Resin development

“…The formation of a thiol-ene network with high elastic modulus, functional conversion, and fast reaction kinetics can lead to similar shrinkage stress. Although delayed gelation supports the previous literature reports [15–18] on stress development in thiol-ene vs. dimethacrylate resins, the examples at hand reveal the important balance that has to be considered between elastic modulus (and stress) development and conversion in highly converted thiol-ene glasses.…”

“…In the past decade, thiol-ene photopolymerization has gained significant attention as a candidate for dental restorative materials [15–18]. Still, despite their high efficiency and many desirable properties, methacrylate-based resins continue to dominate the dental restoratives market.…”

“…Several studies have investigated the feasibility of formulating novel restorative materials that utilize the thiol-ene photopolymerization reactions [15–18]. Due to the step-growth evolution of the network, the thiol and ene monomers are quickly consumed while low molecular weight species dominate in the early stages of the polymerization.…”

Microstructural Features of Current Resin Composite Materials

“…Drawbacks with this technology that have delayed its commercial implementation include the foul odor and stability concerns (shelf-life) associated with thiol-containing materials. As alternatives, thiol-terminated oligomeric additives have been proposed, with increased mechanical properties, increased conversion, and decreased stress [53].…”

Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

“…They prepared a series of organosilicate hydrolyzable monomers combined with trimethylolpropane tris (3-mercaptopropionate) (tri-thiol) in a thiol-ene "click" polymerization reaction to produce clear, colorless thiol-ene networks using radiation and thermal-cure techniques. Reinelt et al synthesized oligomers based on innovative thiol derivative 4a for the production of lowodor and low-shrinkage thiol-ene dental composites, which showed good mechanical properties and reduced shrinkage stress [33].…”