Structure and Adsorption of 3-Acryloxypropyltrimethoxysilane

Abstract

The adsorption of 3-acryloxypropyltrimethoxysilane (APMS) onto silica and structures formed from the adsorption were studied using gravimetric analysis and NMR. APMS molecules were hydrolyzed at room temperature and then condensed at 110 °C with other APMS molecules or on a silica surface. After heat treatment at 110 °C, the alkyl groups of APMS from the bulk species or the immobilized species on the silica surface were investigated using 13C cross-polarization, magic-angle spinning (CP-MAS) NMR. 29Si MAS and CP-MAS NMR techniques showed that most of the APMS silanol groups were condensed to 27% T2 and 73% T3 species during heat treatment at 110 °C. The condensed APMS was then pyrolized at 600 °C. Most of the APMS alkyl groups had been replaced with oxygen during pyrolysis resulting in 21% Q3 and 79% Q4 species. The differences in the masses of APMS following the heat treatment steps (at 110 °C and 600 °C) made it possible to confirm the nature of the chemical species present. From the gravimetric measurements, there were 26% T2 and 74% T3 species after 110 °C heat treatment and 18% Q3 and 82% Q4 species after pyrolysis. The results from NMR and gravimetric analysis were in good agreement. A Langmuir isotherm was applied to estimate the saturated layer coverage of APMS, which was determined using the mass profile of APMS adsorbed on a high-surface-area fumed silica; it showed the saturated layer coverage to be about 0.6 mmol/100 m2.

FTIR thermal analysis on organofunctionalized silica gel

“…For grafting aromatic groups onto the silica surface, the use of an intermediate reagent such as 3-chloropropyltrimethoxysilane or 3-aminopropyltrimethoxysilane, as bridging molecules was necessary 2,[5][6][7][8] . After the intermediate reactions the aromatic groups could be immobilized.…”

“…Stable bonded organic groups on a silica gel surface can be obtained using a grafting synthesis. The organosilane Y 3 Si-R-X is a very common agent used in the grafting process 2,[5][6][7][8] , Y is usually a halide or alkoxy group, R a linear chain and X an halide or amine group. Using a SN 2 reaction, the immobilization of several organic groups can be achieved.…”

Surface modification of oxidic nanoparticles using 3-methacryloxypropyltrimethoxysilane

“…Only some of these studies mention the quantitative amount of the grafted molecules [3][4][5][6][7][8][9]. The experimentally determined maximum values for the surface coverage of oxides by MPS range from 2.8 to 7.5 µmol/m 2 , depending on the type of oxide.…”

Silane Coupling Agents

“…With a heating rate of 10 • C/min, the organic portion of the coupling agent volatilizes off the surface between 300 and 600 • C. At moderate temperatures, such as 100 • C, the coupling agents are relatively stable. The SiO portions of the coupling agent molecule, along with the rest of the silica, remain intact on the surface (18). Knowledge of the beginning and ending masses provide a reasonable measurement of the amount of coupling agent bound to the surface.…”

“…5 for adsorbed and heat-treated APMS on a silica surface (18). The spectra were taken with magic angle spinning and cross-polarization.…”