The Synthesis Of Methacrylate Monomers With Low Polymerization Shrinkage And The Application In Root Canal Sealer

The low viscousity monomer, such as triethylene glycol dimethacrylate (TEGDMA), was used as diluent because of the high viscosity of its basic resin Bisphenol A glycidyl dimethacrylate (Bis-GMA) in methacrylates root canal sealer. However, the addition of TEGDMA diluent leads to increase the polymerization shrinkage evidently and make the therapy fail. In order to overcome the drawback, in this thesis the two novel methacrylates-terminated with high molecular volume and high molecular weight are synthesized. They were used as reactive diluents and composited with Bis-GMA to decrease both viscosity and polymerization shrinkage. The most significant innovation in this thesis is that the two novel methacrylates-terminated three-branched oligomers diluents are originative. The results are as follows:1. The novel mono-methacrylates-terminated oligomer GPTEMA with three long-branched chain structures was synthesized through the reaction of glycerol propoxylate triglycidyl ether (GPTE) and methacrylic acid. Its structure was confirmed by FT-IR, 1H-NMR, gel permeation chromatography and element analysis. The GPTEMA was used as reactive diluent to prepare a series of Bis-GMA/TEGDMA/GPTEMA copolymers. The results illustrated that the Bis-GMA/TEGDMA/GPTEMA copolymers have lower polymerization shrinkage, higher double bond conversion, lower Tg, lower flexural strength and flexural modulus, higher water sorption and higher diffusion coefficient when content of GPTEMA increased.2. The di-methacrylates-terminated oligomer GPTEMA-MA with three long-branched chain structures was synthesized through GPTEMA and methacrylic anhydride. Its structure was confirmed by FT-IR, 1H-NMR, gel permeation chromatography and element analysis. The GPTEMA-MA was used as reactive diluents to prepare a series of Bis-GMA/TEGDMA/GPTEMA-MA copolymers. The effects of GPTEMA-MA on properties of Bis-GMA/TEGDMA/GPTEMA-MA resin system were investigated. The results illustrated that the Bis-GMA/TEGDMA/GPTEMA-MA copolymer have lower polymerization shrinkage, higher double bond conversion, lower flexural strength and flexural modulus, higher water sorption, higher diffusion coefficient, higher Tg with increasing content of GPTEMA-MA, but its water solubility has no obvious change.3. The barium glass powder was used as the inorganic filler to be added in Bis-GMA/TEGDMA/GPTEMA-MA resin system to formulate a novel root canal sealer. The effects of barium glass powder on the properties of root canal sealers were investigated. The results illustrated that with increasing content of barium glass powder, the polymerization shrinkage of the root canal sealer decreased further, the double bond conversion first increase then the decrease, water sorption and diffusion coefficient increased evidently, the contact angles and the water-resistance increased greatly, the flexural strength decreased slightly, but the flexural modulus increased greatly.