Reactions in aminosilane‐epoxy prepolymer systems. II. Reactions of alkoxysilane groups with or without the presence of water

Abstract

SYNOPSISThe hydrolysis and reactions of alkoxy silane groups have been studied on a model compound ( T A ) prepared from 2 mol of phenyl glycidyl ether and 1 mol of aminopropyl triethoxy silane. At low (40°C) and high (140°C) temperatures, the monomer conversion and the evolution of the molecular mass are followed by size exclusion chromatography (SEC) .During the same reaction time, the evolution of the functional groups, hydroxyl CH-OH, ethoxy -O-CC2H5, and siloxane Si-0-Si, is observed by FTIR spectroscopy. Without the presence of water, reactions between hydroxyl and ethoxy silane lead to gelation at the end of the reaction. A by-product, probably a cyclic tetramer is also formed. After the hydrolysis, the reaction of the model compound is quite different. The product of reaction is always soluble, even after a treatment a t high temperatures, and the evolution of the molecular mass versus the reaction time seems to correspond to the condensation giving a dead cyclic tetramer. From this study it is evident that the curing cycle has a great influence on the properties of the interface of a composite based on a epoxy matrix.

Measurement of the extent of reaction of an epoxy–cycloaliphatic amine system and influence of the extent of reaction on its dynamic and static mechanical properties

“…The phenyl group band ( 1180 cm-') was used as a reference since it is assumed to be unmodified during the reaction. 21 The disappearance of the epoxy functions was followed with the height of the epoxy band (915 cm-') with respect to the phenyl band height.…”

Bridged Silsesquioxanes with Organic Domains Self‐Assembled as Functionalized Molecular Channels

“…These peaks indicate the formation of oligomers of the desired precursor ( Figure 1) by the reaction of Si(OCH 3 ) groups with the secondary hydroxyls produced in the epoxy-amine reaction. [27][28][29][30] The covalent Si-O-C bonds generated in this reaction were hydrolyzed together with the remaining Si(OCH 3 ) groups by the addition of formic acid during the formation of the bridged silsesquioxane. [29][30][31][32] Characterization of the Bridged Silsesquioxanes…”

Fast Synthesis of Nanostructured Microspheres of a Bridged Silsesquioxane via Ultrasound‐Assisted Sol–Gel Processing

“…The epoxy-amine reaction led not only to the desired precursor but also to the formation of oligomers produced from Si(OCH 3 ) groups which reacted with the secondary hydroxyls generated by opening of the epoxy ring. In this way, oligomers are formed through covalent Si-O-C bonds, [30][31][32][33] leading to a viscous solution. However, these Si-O-C bonds may be hydrolyzed along the course of the hydrolytic condensation, [32] particularly when using an acid catalyst.…”