A new fluorinated urethane dimethacrylate with carboxylic groups for use in dental adhesive compositions

A urethane macromer containing hexafluoroisopropylidene, poly(ethylene oxide) and carboxylic moieties (UF-DMA) was synthesized and used in proportions varying between 15 and 35 wt.% (F1-F3) in dental adhesive formulations besides BisGMA, triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The FTIR and 1H (13C) NMR spectra confirmed the chemical structure of the UF-DMA. The experimental adhesives were characterized with regard to the degree of conversion, water sorption/solubility, contact angle, diffusion coefficient, Vickers hardness, and morphology of the crosslinked networks and compared with the specimens containing 10 wt.% hydroxyapatite (HAP) or calcium phosphate (CaP). The conversion degree (after 180 s of irradiation with visible light) ranged from 59.5% (F1) to 74.8% (F3), whereas the water sorption was between 23.15 μg mm− 3 (F1) and 40.52 μg mm− 3 (F3). Upon the addition of HAP or CaP this parameter attained values of 37.82-49.14 μg mm− 3 (F1-F3-HAP) and 34.58-45.56 μg mm− 3, respectively. Also, the formation of resin tags through the infiltration of a dental composition (F3) was visualized by SEM analysis. The results suggest that UF-DMA taken as co-monomer in dental adhesives of acrylic type may provide improved properties in the moist environment of the mouth.