Thermal property of epoxy/SiO₂ hybrid material synthesized by the sol–gel process

Abstract

Organic-inorganic hybrid materials synthesized by the sol-gel process have been developed for several years. This synthesis method can effectively overcome the defects of conventional composite materials. In this investigation, epoxy/SiO 2 hybrid material was synthesized by a sol-gel process with a precursor system. Tetraethoxysilane, water, and ethanol were mixed in appropriate proportions, varying the amounts of catalyst, alkalinity, and acidity, and then processed by a hydrolysis-condensation reaction at room temperature. The product synthesized with this process is called a precursor. The coupling agent ␥-glycidoxypropyl-methyldiethoxysilane (KBE-402) was used to modify the surface of the silica. The role of the coupling agent was to add covalent bonding between epoxy resin and silica, which reinforced the interfacial force of the hybrid material. The epoxy resin was mixed with precursor in different proportions and then cured at 170°C for 1 h. The thermal property of the epoxy/SiO 2 hybrid materials was studied by thermogravimetric analysis and DSC. From the results, we found the precursor prepared with acidity catalyst was better than that prepared with alkalinity catalyst. Coupling agent improved the thermal property of epoxy/ SiO 2 hybrid materials, especially when the temperature was high and the suitable amount of the coupling agent for the hybrid system was 5%. The glass-transition temperature of the hybrid materials was increased to adapt to the content of precursor from 80 to 113°C.

Hyperbranched Polymer/TiO2 Hybrid Nanoparticles Synthesized via an In Situ Sol‐Gel Process

“…DLS measurements were performed to investigate the formation of some primary particles in the solution before the thermal curing process and the results are shown in Figure 1. In the case of the DMAc solution of the HBP-OH polymer, the main peak is centered at about 1.7 nm, while after the addition of 20 wt.-% Ti(iOPr) 4 and H 2 O, the peak is shifted at about 8 nm. This result indicates the formation of some primary particles which are stabilized through the interactions with the HBP polymer functionalities.…”

“…A second solution, made up of Ti(iOPr) 4 (in the amount of 7.5, 10, and 20 wt.-% with respect to the polymer) and 5 mL of DMAc, was added very slowly for 1 h, drop by drop and under vigorous stirring at room temperature. In the end, a mixture of water [in equimolar amount respect to the Ti(iOPr) 4 ] and DMAc was added dropwise for over 1 h in the reaction solution. As result, a perfectly clear yellow solution was obtained.…”

“…To the resulting solutions, the curing agent 1,6-diisocyanatohexane and a catalyst dibutyltin dilaurate were added directly, films were coated on a glass substrate, and then they were heated under vacuum at 70 8C for 2 d. Considering the condensation reaction of the Ti(iOPr) 4 precursor, after complete curing, theoretically 1.4, 2.8, or 5.6 wt.-% TiO 2 should be incorporated in the composite.…”

“…At the same time, it allows the curing of the polymer, thanks to the reaction between the isocyanate groups of the curing agent and the OH end groups, which are present in both the HBP structures employed. The synthesis of the TiO 2 particles, however, would have started already in the solution due to high reactivity of the precursor Ti(iOPr) 4 . DLS measurements were performed to investigate the formation of some primary particles in the solution before the thermal curing process and the results are shown in Figure 1.…”

“…In particular, polymers combined with metal oxides nanoparticles can, as reported in the literature, lead to composites characterized by improved chemical, thermal, optical, electronic, and mechanical properties. [2][3][4][5][6][7] The incorporation of titanium oxide nanoparticles in thin films and coatings is especially encouraging since by this surface hardness can be significantly improved and, on the other hand, self-cleaning and antimicrobial properties can be introduced based on the photocatalytic effect induced by some titanium oxide modification.…”