Poly(methyl methacrylate)-titania hybrid glasses were synthesized by sol-gel processes using acrylic acid or allyl acetylacetone as coupling agent. Titanium butoxide modified with acrylic acid (or titanium isopropoxid...Poly(methyl methacrylate)-titania hybrid glasses were synthesized by sol-gel processes using acrylic acid or allyl acetylacetone as coupling agent. Titanium butoxide modified with acrylic acid (or titanium isopropoxide modified with allyl acetylacetone) was hydrolyzed to produce a titania network, and then poly(methyl methacrylate) (PMMA)chains formed in situ through a radical polymerization were chendcally bonded to the fortheng titania network to synthesize a hybrid glass. Transparent hybrid glasses with different contents of titania were achieved. With the increase of the titania content, the color of the products changed from yellow to red. The synthesis process was investigated stepwise by using FTIR spectroscopies, and the experimental results demonstrated that acrylic or acetylacetonate groups bound to titanium remain in the final hybrid glasses.The thermal stability of the hybrid materials were considerably improved relative to pure PMMA. The hybrid glasses using allyl acetylacetone as coupling agent exhibited ther mochromatic effect which both pure PMMA and titan ia do not manifest.展开更多
Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and superc...Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.展开更多
文摘Poly(methyl methacrylate)-titania hybrid glasses were synthesized by sol-gel processes using acrylic acid or allyl acetylacetone as coupling agent. Titanium butoxide modified with acrylic acid (or titanium isopropoxide modified with allyl acetylacetone) was hydrolyzed to produce a titania network, and then poly(methyl methacrylate) (PMMA)chains formed in situ through a radical polymerization were chendcally bonded to the fortheng titania network to synthesize a hybrid glass. Transparent hybrid glasses with different contents of titania were achieved. With the increase of the titania content, the color of the products changed from yellow to red. The synthesis process was investigated stepwise by using FTIR spectroscopies, and the experimental results demonstrated that acrylic or acetylacetonate groups bound to titanium remain in the final hybrid glasses.The thermal stability of the hybrid materials were considerably improved relative to pure PMMA. The hybrid glasses using allyl acetylacetone as coupling agent exhibited ther mochromatic effect which both pure PMMA and titan ia do not manifest.
文摘Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.
