INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Photobleaching of camphorquinone during polymerization
Autor/es:
SILVANA V. ASMUSSEN; WALTER F. SCHROEDER; CLAUDIA I. VALLO
Lugar:
Los Cocos, Argentina
Reunión:
Simposio; V Simposio Binacional de Polímeros Argentino-Chileno, ARCHIPOL; 2009
Institución organizadora:
Sociedad Chilena de Química – Asociación Argentina de Polímeros
Resumen:
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.