In order to investigate dye-dispersion behaviors in organic-inorganic hybrids, we incorporated RGB lightemitting organoboron dyes (1,3-diketonate BF 2 complex, borondipyrromethene (BODIPY), and boron di(iso)indomethene as blue, green and red light-emitting dyes, respectively) into poly(2-hydroxyethyl methacylate) (PHEMA)-silica hybrids prepared by the microwave-assisted technique. Photoluminescence spectra of two dyes in various concentrations and Stern-Volmer plots indicate that the energy transfer efficiencies between the dyes in the hybrids were lower than that in the solution state, resulting from the suppression of concentration-quenching. Furthermore, we demonstrate the color tuning for preparing white light-emitting hybrids based on simultaneous RGB light-emission of the organoboron dyes. Finally, pure white light-emitting hybrids were obtained by the microwave-assisted in situ method.
We prepared imidazolium-containing silica hybrid films by sol-gel reactions of 1-(trimethoxysilylpropyl)-3-methylimidazolium chloride under microwave irradiation. Furthermore, we incorporated hydrophobic dyes such as pyrene and 1-pyrenecarboxaldehyde into the silica hybrids, and we investigated the dispersion behaviors of these dyes in the matrices. The local heating of the imidazolium groups under microwave irradiation was suggested to contribute to the enhancement of reaction rates in the sol-gel process. Finally, we achieved the incorporation of higher dye concentrations in the silica hybrids compared with those achieved with conventional heating.
A facile and fast synthesis of poly(2-hydroxyethyl methacrylate) (PHEMA)/silica hybrid was achieved using in situ polymerization method under microwave irradiation, in which the polymerization of 2-hydroxyethyl methacrylate (HEMA) was carried out together with the sol-gel reaction of methyltrimethoxysilane (MeTMOS). The preparation rate of the hybrid under microwave irradiation was accelerated rapidly relative to that under conventional heating due to the activation of hydroxyl groups of HEMA and silanol groups of alkoxysilanes by microwave irradiation. When acetic acid was used as a catalyst for the sol-gel reaction of MeTMOS, the transparency of the hybrid was improved. The transparency, homogeneity, and formability of the hybrid prepared under microwave irradiation were better than those prepared under conventional heating. In addition, it was found that the degree of polymerization of HEMA under microwave irradiation is higher than that under conventional heating by using FT-IR spectroscopy due to the activation of the polymerization of HEMA. Thermal properties of the hybrids prepared under microwave irradiation were almost identical to those under conventional heating.The methodology of microwave irradiation has attracted growing attention in the field of organic chemistry as an alternative heating method.
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