Model ternary thiol−ene/acrylate photopolymerization involving acrylate homopolymerization and copolymerization of thiol−ene and thiol−acrylate monomers were monitored by real-time FTIR. In all ternary mixtures, including those prepared with different acrylate concentrations, acrylate conversion was 100%. However, thiol−ene conversions were found to be controlled by their initial concentrations. The influence of acrylate monomer chemical structure on the thermophysical properties of ternary thiol−ene/acrylate systems was studied with DMA, DSC, and the absorbance of a nondestructive impact energy. The addition of acrylate to the thiol−ene system increased the rubbery modulus while the tan δmax shifted to higher temperatures. Densely cross-linked, heterogeneous matrix formation was observed with the broadening of tan δ peaks at high acrylate concentrations. The high impact absorption of these ternary thermoset photopolymers was correlated with the dynamic mechanical damping ability of the networks. Acrylates with higher functionality and low molecular weight per double bond are more effective at increasing the glass transition temperature of the thiol−ene polymer network. Fracture behavior of ternary thiol−ene/acrylate networks under impact shows a dependence on the chemical structure of the acrylate, component concentrations, and low-temperature relaxation processes. The ternary matrix formed with a bisphenol A based difunctional acrylate monomer exhibited improved impact energy absorption at room temperature. Finally, tensile properties of polymer networks formed with thiol−ene/acrylate and thiol−acrylate mixtures are given for comparison purposes.

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Urethane-based multiene monomers were synthesized and photopolymerized with a trifunctional thiol monomer to form highly cross-linked thiol−ene networks. Real-time FTIR was used to monitor the conversion of thiol and urethane ene monomers as a function of irradiation time. For stoichiometric thiol−urethane ene photopolymerizations, monomers reacted in a 1:1 molar functional group ratio, reaching ∼90% monomer conversion within several seconds. The effects of the ene chemical structure and concentration on thermal and mechanical properties were characterized by DMA, DSC, TGA, tensile, and energy absorption upon nondestructive impact. The temperature at tan δmax of the thiol−urethane ene networks was around 39 °C and decreased to lower temperatures with the addition of a reactive diluent diallyl ether ene monomer. Tensile and impact results were combined with fracture toughness measurements to elucidate the effect of the urethane and bisphenol A chemical structures. The energy absorption was dependent on the glass transition temperature of the thiol−urethane ene cross-linked networks. Improvement in fracture toughness and tensile properties was observed with the incorporation of 10 mol % of an ene with a bisphenol A structure. Scanning electron micrographs of fractured surfaces were used to interpret the nature of the brittle fracture. All of the properties of the thiol−urethane ene networks were compared to a conventional trithiol−triallyltriazine trione-based matrix.

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Objective: To provide athletic trainers, health care professionals, and all those responsible for the care of athletes with clinical recommendations for preventing and managing sportrelated dental and oral injuries.Background: Participation in competitive sports continues to grow at both the interscholastic and intercollegiate levels. Therefore, exposure to, and the incidence of athletic-related injury, including orofacial injury, will also likely increase. At the time of this writing, the leading governing agencies for interscholastic (National Federation of State High School Associations) and intercollegiate (National Collegiate Athletic Association) sports require only protective orofacial equipment (eg, mouthguards) for 5 and 4, respectively, of their sanctioned sports. Although orofacial injuries represent a small percentage of all sport-related injuries, the financial burden associated with these injuries (eg, tooth avulsion) can exceed $15 000 over an adult life. Therefore, effective management of sport-related dental injuries is critical to the long-term financial, physical, and emotional health of people who have experienced dental trauma.Recommendations: Based upon the current evidence regarding sport-related orofacial injury, we provide recommendations related to planning considerations, education, and mouthguard efficacy, material, fabrication, and care considerations. Additionally, suggested best practices for managing sport-related dental injury are also given for athletic trainers and other health care professionals.