Condensation of alkoxysilanes in alcoholic media: II. Oligomerization of aminopropylmethyldiethoxysilane and co‐oligomerization with dimethyldiethoxysilane

Abstract

In the context of the preservation of cultural heritage, the treatment of paper by an aminoalkylalkoxysilane, or its mixture with dimethyldiethoxysilane (DMDES), gave encouraging results. The condensation experiments presented here, carried out in alcohol medium using aminopropylmethyldiethoxysilane (AMDES) alone or with DMDES, were followed using 1 H NMR, 29 Si NMR and matrix-assisted laser desorption ionization time-of-flight (MALDI TOF) spectroscopies. The aim was to determine whether DMDES and AMDES could copolymerize under the conditions used. An exchange reaction was observed for AMDES in ethanol in the absence of water, under conditions where no exchange took place for DMDES. In methanol, this reaction proceeded much more rapidly and the reactivity of methoxysilyl groups was higher than that of ethoxysilyl groups. In the same solvent, in the presence of water, hydrolysis, cyclization and oligomerization were observed using NMR and MALDI TOF spectroscopies. In ethanol, a kinetic study of a mixture of DMDES and AMDES showed that the condensation of the two monomers proceeded at comparables rates and MALDI-TOF analysis gave evidence that mixed oligomers were produced, containing from one to four AMDES units. It was concluded that the co-oligomerization did not lead to a mixture of homo-oligomers, which would be due to different hydrolysis and condensation kinetics, but induced the formation of co-oligomers.

An s‐triazine briged silylalkyl sol–gel precursor—synthesis, structure and coating formation for electrical insulation of copper wire and corrosion protection of construction steel

“…The disilanol was observed at −8.8 ppm. The location of the signal corresponds to comparable compounds like dimethyldiethoxysilane or other alkylated dialkoxysilanes . Next to the disilanole another signal at −8.9 ppm is observed.…”

“…The location of the signal corresponds to comparable compounds like dimethyldiethoxysilane or other alkylated dialkoxysilanes. [46][47][48][49] Next to the disilanole another signal at À8.9 ppm is observed. This signal can be ascribed to a cyclic structure that is formed by condensation of three silanol units ( cy3 D).…”

“…After curing the materials at 200°C for 30 min, one major signal at À20.9 ppm is observed. This signal can be assigned to completely condensed D 2 group [46][47][48][49] (see Fig. 8).…”

“…At À8.9 ppm, another signal can be identified that corresponds to cyclic structures. [47][48][49] After 30 min at 300°C, new silicon environments are observed that can be traced back to a species with a higher degree of condensation, i.e. the D 2 groups (RR′SiO 2 moieties) were partially oxidized to T groups (RSiO 3 units).…”

Lightweight foams of amine-rich organosilica and cellulose nanofibrils by foaming and controlled condensation of aminosilane

“…The chemical shift scale was calibrated with the chemical shifts for the dimeric compounds of the organosilane monomer 3-aminopropyl(methyl)diethoxysilane. 54 The temperature scale was externally calibrated with the temperature dependent chemical shifts of methanol. 55…”