title: The effects of light intensity, temperature, and comonomer composition on the polymerization behavior of dimethacrylate dental resins.
abstract: One of the most common combinations for the organic phase of dental restorative materials is BisGMA (2,2bis[4-(2-hydroxy-3-methacryloyloxypropoxy) phenyl]propane) and TEGDMA (triethylene glycol dimethacrylate). However, this copolymer has some drawbacks, such as volume shrinkage during cure and lack of complete double-bond conversion. If the properties of this system are to be improved, an attempt must be made to understand the underlying kinetics of the reaction. This work examines the effects of light intensity, temperature, and composition on the polymerization behavior of BisGMA/TEGDMA copolymerizations. Using differential scanning calorimetry, we monitored the rates of photopolymerization for various experimental conditions. The BisGMA/TEGDMA copolymerization behaved similarly to other dimethacrylate systems and exhibited diffusion-controlled kinetics. It was found that the maximum rate of polymerization was significantly affected by the intensity of the light, and the temperature of the polymerization affected the conversion at which the maximum rate occurred. When the composition of the mixture was varied, it was discovered that the viscosity of the system played a significant role in the polymerization rate and the onset of reaction-diffusion-controlled termination. Mixtures which contained from 50 wt% to 75 wt% BisGMA displayed the highest maximum rate. This feature suggests that TEGDMA is an excellent diluent, since it increases the mobility of the reacting medium; however, the high reactivity is due to the presence of BisGMA. Therefore, based on compositional dependence, we conclude that the BisGMA portion of the mixture largely controls the polymerization mechanisms and kinetics.
authors.affiliation: Department of Chemical Engineering, University of Colorado, Boulder 80309-0424, USA.
authors.forename: L G
authors.initials: LG
authors.lastname: Lovell
authors.forename: S M
authors.initials: SM
authors.lastname: Newman
authors.forename: C N
authors.initials: CN
authors.lastname: Bowman
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000138:chemical synthesis / Q000737:chemistry*; D003764:Dental Materials / Q000138:chemical synthesis / Q000737:chemistry*; D004058:Diffusion; D006801:Humans; D007700:Kinetics; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000138:chemical synthesis / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D011108:Polymers; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate