Science and Technology Production
Congress
Authorship
Silvana V. Asmussen
;
SCHROEDER, WALTER FABIAN
;
Claudia I. Vallo
Date
2009
Publishing House and Editing Place
V Simposio Binacional de Polímeros Argentino-
Summary
Information provided by the agent in
SIGEVA
The purpose of this research was to test the hypothesis that the photobleaching of camphorquinone (CQ) during photopolymerization of dimethacrylate-based monomers is affected by the structure of the monomers. The photodecomposition rate of CQ/amine system in polymerizing monomers was evaluated at different light intensities. The photobleaching of the CQ was studied by monitoring the decrease in light absorption as a function of continuous irradiation time. The absorption changes were assessed b...
The purpose of this research was to test the hypothesis that the photobleaching of camphorquinone (CQ) during photopolymerization of dimethacrylate-based monomers is affected by the structure of the monomers. The photodecomposition rate of CQ/amine system in polymerizing monomers was evaluated at different light intensities. The photobleaching of the CQ was studied by monitoring the decrease in light absorption as a function of continuous irradiation time. The absorption changes were assessed by recording the transmitted light that passed through samples of monomers containing CQ/amine. The photobleaching of CQ in 2,2- bis[4-(2-methacryloxyethoxy)phenyl]propane (bis-EMA) and 2,2-bis[4-(2-hydroxy-3-methacryloxyprop-1-oxy)phenyl]propane (bis-GMA) is not sensitive to the mobility of the medium, which changes from relatively viscous resins to glassy networks. However, the CQ reduction in 1,6-bis (methacrylyloxy-2-ethoxy-carbonylamino)-2,4,4-trimethylhexane (UDMA) can be described by two constant rates. During the first part of the irradiation, the CQ decomposition rate constant value is similar to that of the bis-EMA and bis-GMA. Whereas at prolonged irradiation times the rate constant is markedly reduced. This behavior may be attributed to a restricted mobility of the network, which favors the deactivation of the CQ excited states and leads to a reduced CQ photobleaching rate.
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Key Words
PHOTOINITIATORDIMETHACRYLATE RESINPHOTOPOLYMERIZATIONDENTAL POLYMERS