Influence of solvent on the physical and lasing properties of dye-doped sol–gel host

Anticorrosion properties of silica-based sol-gel coatings on steel – The influence of hydrolysis and condensation conditions

“…Moreover, the sol-gel method used to obtain the coatings does not generate waste products that must either be removed or treated. Synthesis is usually prepared at room temperature, without the input of additional energy [3][4][5][6]. Sol-gel materials are becoming increasingly popular across a wide range of potential applications, such as in optical [4], automotive [7], aircraft [8], medicine [9], chemical industries [10], and other application areas [5].…”

“…On another level, it can be seen that a critical parameter is recognizing the nature of the interaction between the solvent and the solute, such as the intermolecular forces and energy barriers that exist between the reactants, the degree of polarity and energy input that exist between polar and non-polar molecules, and the influence of the dielectric constant on the overall chemical equilibrium, where increasing the dielectric constant causes a decrease in the force between the molecules during the formation of the structure [4,14,21,22]. Because the byproducts of the synthesis are water and alcohol, selection of appropriate solvents may significantly influence the end-structure of sol-gel materials.…”

“…Because the byproducts of the synthesis are water and alcohol, selection of appropriate solvents may significantly influence the end-structure of sol-gel materials. According to the literature [4,14,18], the solvent phase acts as an agent between siloxanes and water, promoting the uniform dispersal of the reactants during the hydrolysis and condensation reactions of the solgel precursors and enables a faster rate of water evaporation. Using a solvent with a high dielectric constant restricts intermolecular reactions and, as a result, decreases the kinetics of the condensation, thereby decreasing the degree of conversion of the reactants to the gel form [14].…”

“…Using a solvent with a high dielectric constant restricts intermolecular reactions and, as a result, decreases the kinetics of the condensation, thereby decreasing the degree of conversion of the reactants to the gel form [14]. Moreover, aprotic solvents are more inert to the type of chemical reactions that drive the sol-gel process [4]. Based on their use of a polar and protic solvent (ethanol), Khan et al [4] obtained a stiffer and condensed sol-gel structure with small pores, while the opposite was observed with an aprotic solvent, resulting in decreased homogeneity and an increase in the pore-size of the matrix.…”

“…Moreover, aprotic solvents are more inert to the type of chemical reactions that drive the sol-gel process [4]. Based on their use of a polar and protic solvent (ethanol), Khan et al [4] obtained a stiffer and condensed sol-gel structure with small pores, while the opposite was observed with an aprotic solvent, resulting in decreased homogeneity and an increase in the pore-size of the matrix. Additionally, their research suggests that aprotic solvents promote irreversible hydrolysis and condensation reactions [4].…”