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Self-Strengthening Hybrid Dental Adhesive via Visible-light Irradiation Triple Polymerization
Song, Linyong ; Ye, Qiang ; Ge, Xueping ; Misra, Anil ; Tamerler, Candan ; Spencer, Paulette
Song, Linyong
Ye, Qiang
Ge, Xueping
Misra, Anil
Tamerler, Candan
Spencer, Paulette
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Abstract
A self-strengthening methacrylate-based dental adhesive system was developed by introducing an epoxy cyclohexyl trimethoxysilane (TS) which contains both epoxy and methoxysilyl functional groups. The experimental formulation, HEMA/BisGMA/TS (22.5/27.5/50, wt%), was polymerized by visible-light. Real-time Fourier transform infrared spectroscopy (FTIR) was used to investigate in situ the free radical polymerization of methacrylate, ring-opening cationic polymerization of epoxy, and photoacid-induced sol-gel reactions. Among the three simultaneous reactions, the reaction rate of the free radical polymerization was the highest and the hydrolysis/condensation rate was the lowest. With 40s-irradiation, the degrees of conversion of the double bond and epoxy groups at 600 s were 73.2±1.2%, 87.9±2.4%, respectively. Hydrolysis of the methoxysilyl group was initially <5%, and increased gradually to about 50% after 48 h dark storage. Photoacids generated through the visible-light-induced reaction were effective in catalyzing both epoxy ring-opening polymerization and methoxysilyl sol-gel reaction. The mechanical properties of copolymers made with TS concentrations from 5 to 35 wt% were obtained using dynamic mechanical analysis (DMA). In wet conditions, the storage moduli at 70 °C and glass transition temperature were significantly higher than that of the control (p<0.05); these properties increased with TS concentration and storage time. The post reaction of hydrolysis/condensation of alkoxysilane could provide persistent strengthening whether in a neutral or acidic environment and these characteristics could lead to enhanced mechanical properties in the oral environment. The cumulative amount of leached species decreased significantly in the TS-containing copolymers. These results provide valuable information for the development of dental adhesives with reduced leaching of methacrylate monomers and enhanced mechanical properties under the wet, oral environment.
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2016-05-25
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Royal Society of Chemistry
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Song, L., Ye, Q., Ge, X., Misra, A., Tamerler, C., & Spencer, P. (2016). Self-Strengthening Hybrid Dental Adhesive via Visible-light Irradiation Triple Polymerization. RSC Advances, 6(57), 52434–52447. http://doi.org/10.1039/C6RA09933E