Glycerol dimethacrylate

BisGMA (Polysciences, Warrington, PA) and HEMA (Acros Organics, NJ) were used as received without further purification as monomers in dentin adhesives. BMPB was synthesized as reported previously in our laboratory.^{30 (link)} 4-((1,3-Bis(methacryloyloxy)propan-2-yl)oxy)– 2-methylene-4-oxo-butanoic acid (BMPMOB) was synthesized in our laboratory and used as a comonomer (Figure 1). Itaconic anhydride (IAA) and glycerol dimethacrylate (GDMA) were obtained from Sigma-Aldrich (St. Louis, MO). Camphoroquinone (CQ), ethyl-4-(dimethylamino) benzoate (EDMAB), and diphenyliodonium hexafluorophosphate (DPIHP) were obtained from Sigma-Aldrich. All other chemicals were reagent grade and used without further purification.

2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]-propane (BisGMA, Polysciences, Warrington, PA) and 2-hydroxyethylmethacrylate (HEMA, Acros Organics, NJ) were used as received without further purification, as monomers in dentin adhesives. Two siloxane methacrylate monomers (SM1 and SM2) were synthesized in our lab. The control adhesive resin consisted of HEMA and BisGMA with a mass ratio of 45/55. This control was used to compare with the experimental adhesive resins with HEMA / BisGMA / SM = 45/55-x/x (w/w) ratio. The control and experimental adhesives were also formulated with 12 wt % water to simulate bonding in the mouth. The concentration of water was based on the total final weight of the adhesive resin. Camphorquinone (CQ, 0.5 wt %), ethyl-4-(dimethylamino) benzoate (EDMAB, 0.5 wt %) and diphenyliodonium hexafluorophosphate (DPIHP,1.0 wt %) were obtained from Aldrich (Milwaukee, WI, USA) and used as a three-component-photoinitiator system without further purification. 2,4,6,8-Tetramethyl-2,4,6,8-tetrakis (propyl glycidyl ether) cyclotetrasiloxane (TPGTS), Glycerol dimethacrylate (GDMA, assay 85%, mixture of isomers), ethyl acetate, boron trifluoride diethyl etherate (BF₃O(C₂H₅)₂), anhydrous magnesium sulfate (MgSO₄), and all other chemicals were purchased from Sigma-Aldrich at reagent grade and used without further purification.