Photopolymerization experiments and properties of some urethane/urea methacrylates tested in dental composites

Abstract

Hydrophobic silyl-urea/urethane methacrylates (UHM-1, UHM-2) and a modified BisGMA derivative (BisGMA-UMA) were synthesized and used as photopolymerizable co-monomers in the preparation of dental composites, besides other urethane dimethacrylates containing oligoethylene oxide segments and carboxylic groups. The homo- and copolymerization behaviour of the synthesized monomers were investigated by FTIR spectroscopy using camphorquinone (CQ) and 4-(dimethylamino)-phenylacetic acid (DMPheAA) as a photoinitiating system, as well as by photo-DSC. The first hybrid monomethacrylate, N-(methacryloyloxyethyl-N’-diethoxymethylsilylpropyl)-urea showed the highest value for the maximum polymerization rate (0.117 s−1) followed by BisGMA analogue (0.085 s−1) and N-methacryloyloxyethyl-N’-bis(triethoxysilylpropylcarbamoyloxyethyl)-urea (0.069 s−1), whereas the degree of conversion decreased from 75.1% (UHM-2) to 41.6% (BisGMA-UMA). Polymerization shrinkage (PS) measured by picnometry for the mixture BisGMA-UMA/TEGDMA (4.78 vol.%) was lower than that exhibited of the control organic matrix BisGMA/TEGDMA (6.85 vol.%) at the same dilution. The addition of one of the obtained monomers into a mixture based on urethane oligomers led to a polymerization shrinkage varying between 8.33 and 6.97 vol.%. A number of properties of the composites formulated with our urethane methacrylates, a urethane dimethacrylate, BisGMA, and glass filler (Zr/Sr glass, quartz, and diatomite) were also determined including the surface damage caused by the Vickers indentation to establish their utility in dentistry.

Effect of cinnamate comonomers on the dental formulation properties

“…Within this context, several urethane (di)methacrylates have been developed in our group including the reactive acid‐functionalized oligomers24, 25 and nonacid ones,26 LC monomers,13 and Bis‐GMA analogous,13, 27 as well as photopolymerizable polyalkenoates,28 to investigate the influence of chemical structure and composition on the photopolymerization process in some dental formulations. Additionally, the study of the properties of photo‐cured networks resulted from the above monomers was essential to understand their behavior in such resin composites.…”

Photopolymerization Pattern of New Methacrylate Cellulose Acetate Derivatives

“…Moreover, the CDs (%) seemed smaller for the films having CA derivatives with intermediate values of FD (%) than CDs (%) of films containing CA-M5 derivative. The intricate process of photopolymerization is subject to various influences, including but not limited to viscosity, the presence of hydrogen bonds, the number and arrangement of photopolymerazable methacylic groups, and the microenvironment [ 60 , 61 ]. Hence, the higher photoreactivity of CA-M100 is most probably due to the existence of an increased number of photopolymerizable groups per CA chain.…”

“…Meanwhile, the higher photoreactivity of CA-M5 may be attributed to a good mobility of polymer chains which ensure a sufficient availability of methacrylic units during photopolymerization. The lower photopolymerization degree achieved for the other CA derivatives with intermediate degrees of functionalization (10%, 25%, and 50%) can be explained by the diffusion restrictions that appeared due to the crosslinking that limits the diffusion of reactive species, and implicitly their accessibility for polymerization, as well as the existence of steric hindrance [ 60 , 61 , 62 ]. However, as can be observed from Figure 12 , the photoreactivity of CA-Mx derivatives can be improved by combining them with one of the oligomers PPG-M or CO-UDMA, which will produce networks with the appropriate double bound transformation and crosslinking density for the intended usage.…”

Viscosity, Degree of Polymerization, Water Uptake, and Water Solubility Studies on Experimental Dichloro-BisGMA-Based Dental Composites

“…Indeed, the viscosity issue of BisGMA necessitates material development; thus, Bis-GMA structural modification including the replacement of its OH groups with low hydrophilic substituents may be one solution. In this context, various derivatives of BisGMA have been synthesized by different researchers, in which the OH functional groups were partially or fully replaced with targeted substituents, including alkyls, aryls, ethers, and esters with small or bulky groups [3,[5][6][7][8][9][10][11][12]. Regardless of the type of substituent used, the viscosity of BisGMA was greatly reduced after modification, confirming that H-bonding is the major cause of its high viscosity character [2,6,10,12,13].…”