Abstract: Objective: To synthesize a light-curable polyurethane(PU) adhesive, and to explore its effects on the water absorption values,the water solubility values,the rates of double blond conversion and the micro-shear bond strength of three commercial resin adhesives. Methods: A polyether PU prepolymer was synthesized by solution polymerization using polyether triol, isophorone diisocyanate,and 2-hydroxyethyl methacrylate as raw materials. The structure of the product was characterized by Fourier transform infrared spectroscopy(FT-IR), and a diluent, a solvent and a photoinitiator were used to prepare a light-curable PU adhesive.The commercial adhesives Single Bond Universal (SBU), Single Bond 2 (SB2) and Clearfil SE (SE) were used as control groups;the SBU,SB2 and SE added with 70%PU adhesives(SBU-70% PU, SB2-70% PU and SE-70% PU) were used as experimental groups. According to the YY 1042-2011 standard, the water absorption values,the water solubility values of the adhesives in experimental groups and control groups were measured.The rates of double bond conversion of the adhesives in various groups were measured by FT-IR. The micro-shear bond strengths of adhesives in various groups were measured using universal testing machine. Results: The FT-IR results showed a characteristic absorption peak of a photo-curable group (C=C double bond) at 1 638 cm^-1, consistent with the expected product structure.The water absorption values of adhensives in experimental groups(SBU-70%PU group,SB2-70%PU group and SE-70%PU group) were significantly lower than those in the corresponding control groups (t=15.479,P<0.05;t=19.703,P<0.05; t=11.795,P<0.05);the solubility values of the adhesives in SBU-70%PU group and SB2-70%PU group were significantly lower than those in the corresponding control groups(t=29.845, P<0.05;t=28.862,P<0.05);the rates of double bond conversion of adhesives in experimental groups were significantly higher than those in the corresponding control groups (t=-11.612,P<0.05;t=7.213, P<0.05;t=-15.031,P<0.05); the micro-shear bond strength of the adhesive in SB2-70%PU group was significantly higher than that in the corresponding control group (t=-2.515,P<0.05). Conclusion: After successfully synthesizing light-curing PU adhesive, and adding 70% PU to the three commercial adhesives, it can significantly reduce the water absorption values and the solubility values of the adhesives, increase the rates of double bood conversion, and it has no significant effect on the micro-shear bond strength, so that the overall properties of the adhesive is effectively improved.

Key words: light curing, polyurethane, dental adhesive, bonding properties