IADR Abstract Archives
Kinetics Studies of Photoinitated Thiol-Michael Addition Reaction
Objectives: To evaluate kinetic parameters for the photobase-initiated thiol-Michael reaction with different thiol and vinyl functional groups. Those kinetic parameters can be used to model resin reaction profiles and improve resin materials selections for dental applications.
Methods: Different mono functional thiol and vinyl monomers were selected for this study. Thiol monomers used for this study include: butyl 3-mercaptopropionate (BMP), butyl thiolglycolate (BT) and hexanethiol (HT). Ethyl vinyl sulfone (EVS), lauryl acrylate (LA), and (hydroxyethyl) methacrylate (HEMA) were used as vinyl monomers for this study.
Kinetic studies were conducted using real-time Fourier transform infrared (FT-IR) to monitor the conversion of thiol ( 2560 cm-1) and vinyl (3050 cm-1) functional groups. The kinetic plots (10%-50% conversion) were then fit to the analytical kinetic model in order to extract kinetic parameters. The kinetic parameters for propagation and chain-transfer were determined by varying the initial stoichiometric ratio of thiol/vinyl concentration (Figure 1).
Results: Table 1 showed the kinetic parameters and reaction orders for various thiol and vinyl functional groups. Ratios of kinetics parameters (Kp/KCT) were found to be highly depend on functional groups and had a significantly impact on reaction order. Similar initial reaction rates between mono-functional and tetra-functional monomer systems suggested that those reaction coefficients can be used to determine and model an equivalent multifunctional thiol-Michael polymerization system.
Conclusions: Kinetics parameters and reaction orders were determined for different thiol and vinyl functionalized monomers. Those kinetics parameters and reaction orders can be used for the development of multifunctional thiol-Michael reaction and their application in dental restorative materials.
Methods: Different mono functional thiol and vinyl monomers were selected for this study. Thiol monomers used for this study include: butyl 3-mercaptopropionate (BMP), butyl thiolglycolate (BT) and hexanethiol (HT). Ethyl vinyl sulfone (EVS), lauryl acrylate (LA), and (hydroxyethyl) methacrylate (HEMA) were used as vinyl monomers for this study.
Kinetic studies were conducted using real-time Fourier transform infrared (FT-IR) to monitor the conversion of thiol ( 2560 cm-1) and vinyl (3050 cm-1) functional groups. The kinetic plots (10%-50% conversion) were then fit to the analytical kinetic model in order to extract kinetic parameters. The kinetic parameters for propagation and chain-transfer were determined by varying the initial stoichiometric ratio of thiol/vinyl concentration (Figure 1).
Results: Table 1 showed the kinetic parameters and reaction orders for various thiol and vinyl functional groups. Ratios of kinetics parameters (Kp/KCT) were found to be highly depend on functional groups and had a significantly impact on reaction order. Similar initial reaction rates between mono-functional and tetra-functional monomer systems suggested that those reaction coefficients can be used to determine and model an equivalent multifunctional thiol-Michael polymerization system.
Conclusions: Kinetics parameters and reaction orders were determined for different thiol and vinyl functionalized monomers. Those kinetics parameters and reaction orders can be used for the development of multifunctional thiol-Michael reaction and their application in dental restorative materials.
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