Kinetics of Alkoxysilanes and Organoalkoxysilanes Polymerization: A Review

Abstract

Scientists from various different fields use organo-trialkoxysilanes and tetraalkoxysilanes in a number of applications. The silica-based materials are sometimes synthesized without a good understanding of the underlying reaction kinetics. This literature review attempts to be a comprehensive and more technical article in which the kinetics of alkoxysilanes polymerization are discussed. The kinetics of polymerization are controlled by primary factors, such as catalysts, water/silane ratio, pH, and organo-functional groups, while secondary factors, such as temperature, solvent, ionic strength, leaving group, and silane concentration, also have an influence on the reaction rates. Experiments to find correlations between these factors and reaction rates are restricted to certain conditions and most of them disregard the properties of the solvent. In this review, polymerization kinetics are discussed in the first two sections, with the first section covering early stage reactions when the reaction medium is homogenous, and the second section covering when phase separation occurs and the reaction medium becomes heterogeneous. Nuclear magnetic resonance (NMR) spectroscopy and other techniques are discussed in the third section. The last section summarizes the study of reaction mechanisms by using ab initio and Density Functional Theory (DFT) methods alone, and in combination with molecular dynamics (MD) or Monte Carlo (MC) methods.

Monitoring Silane Sol-Gel Kinetics with In-Situ Optical Turbidity Scanning and Dynamic Light Scattering

“…The transmissivity patterns along the tube length during the hydrolysis and condensation of nPM are better visualized in the zoomed-in analysis of the first 450 min of the transmissivity curves in Figure 5. Under acid catalysis, ORMOSILs, such as nPM, undergo a stepwise hydrolysis process from (300) to (210), (120), and finally (030) [16,17,18]. With each step, silane solubility increases, leading to near 100% transmissivity, as seen for the nPM data.…”

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“…The solvent was evaporated to give compound 3 as yellow pale oil in quantitative yield. 1 [36]. Thus, subsequent reactions with the use of diamines were directly used in the grafting process to limit the number of stages taken in the whole process.…”

Influence of introducing organic solvents of different nature on the gelation time of a binder based on methylphenyl organosilicon oligomer during curing

“…Предполагаемые химические механизмы процессов катализа в среде с различными растворителями представлены на рисунках 3 и 4 [3,4]. При использовании протонных растворителей происходит формирование комплексного иона гидроксония за счет полярных связей (рис.…”