Controlling the Thermal Polymerization Process of Hybrid Organic−Inorganic Films Synthesized from 3-Methacryloxypropyltrimethoxysilane and 3-Aminopropyltriethoxysilane

Abstract

An important step in the synthesis of hybrid materials is the control of organic chains formation when the organically modified alkoxides are bearing polymerizable groups, such as acrylate or epoxy. Control of the process can be achieved through a deep understanding of the correlation between the synthesis parameters and the final structure. In this paper we have used 3-methacryloxypropyltrimethoxysilane (MPTMS) co-hydrolyzed with tetraethyl orthosilicate (TEOS) using 3-aminopropyltriethoxysilane (APTS) as basic catalyst and network modifier of the structure. The acrylate function in MPTMS has been thermally polymerized and the process has been tuned, with the purpose to reach the highest polymerization efficiency, by controlling the synthesis parameters. The synthesis has been followed in solution by 13 C and 29 Si nuclear magnetic resonance (NMR) spectroscopy, and the structural changes in the films have been studied by Fourier transform infrared spectroscopy (FTIR) as a function of the thermal treatment. Multinuclear solid state NMR spectroscopy on related bulk materials has provided supplementary information on the hybrid network formation. As-deposited films are not fully condensed but a very large conversion of the CdC double bonds (up to 98% of polymerization degree) is achieved during thermal curing by the simultaneous inorganic polycondensation and organic polymerization.

Improved corrosion resistance of AA2024 alloys through hybrid organic–inorganic sol–gel coatings produced from sols with controlled polymerisation

“…The lower the sol concentration, the lower is the intensity of the CfC band at 1639 cm − 1 . The CfO band has three different components [33]: a band at 1705 cm − 1 assigned to CfO hydrogenbonded to OH groups of EGDMA or to Si-OH groups generated in the first stage, a band at 1720 cm − 1 assigned to CfO stretching vibrations that are conjugated to CfC double bonds, and a band at 1732 cm − 1 assigned to C = O stretching vibrations, produced during the organic polymerisation, and not conjugated to C = C double bonds. The ratio of areas of CfC bands between none polymerised and near gelled samples allows determining the polymerisation degree at gelling time as a function of sol concentration.…”

Studies on dialkoxysilane hydrolysis kinetics under alkaline conditions

“…In DMDMS spectrum, the band at 1260 cm À1 is attributed to symmetric deformation vibration of Si-C, which can be used as the internal reference in quantified analysis since its intensity keeps constant during the whole hydrolysis process. The bands at 1190 cm À1 and 1092 cm À1 belong to stretching vibration m (Si-O-C) and show intense bands [2,23]. The characteristic peak at 1190 cm À1 is not overlapped with either methanol or 1, 4-dioxane IR spectra, which can provide the information of the hydrolysis of DMDMS by following its change during the whole hydrolysis process.…”

Photopatterning hybrid sol–gel glass materials prepared from ethylene tellurate and alkoxysilane

“…In the as-deposited film, the presence of absorption bands at 1200 cm À1 , 1168 cm À1 , 1028 cm À1 , 950 cm À1 , and 815 cm À1 indicates that a partial hydrolysis of the alkoxy groups was achieved. The intense O-CH 3 stretching band at 1168 cm À1 was used to monitor the condensation process during UV curing [17]. With the longer time of UV exposure, the intensities of these absorption bands, especially 1168 cm À1 band, decreased gradually, indicating the photopolymerization and condensation of the film.…”