A facile approach for the effect of solution, catalyst and temperature on the synthesis of glass powder by the sol-gel method

Abstract

In this study, the aim is to synthesize borosilicate glass powder with a particle size of approximately 50nm by the sol-gel method to be used as a hierarchical surface agent in hydrophobic coatings. Precursors used in the sol-gel reaction are Tetraethoxysilane (TEOS) as a source of silicon, boric acid as a source of boron and potassium hydroxide as a source of alkali. For this purpose, process optimization was simply investigated in three stages; solution, catalysis and reaction temperature parameters, respectively. In the first stage of the study, gelling behavior and amorphous structure formation were examined by using solutions prepared with different solvents at different pH values. The solution, which had an ethyl alcohol-water mixture as a solvent with an acidic start and alkaline second step, was found to be suitable. In the second step, the effect of catalysis was investigated by changing the catalyst type and amount in the solution which was found to be most suitable in the previous stage. Ammonium hydroxide and urea solutions that contain ammonium groups were used as catalysts. It was observed that the urea solution did not function as a catalyst due to its neutral character versus the base character of the ammonium hydroxide. In the last step of the study, the effect of reaction temperature was investigated. Upper and lower temperatures are limited due to the solution-based process. A temperature close to room temperature was included in the experiment in order to increase the controllability of the temperature. The gelation behavior at all stages was recorded with photoshoots of tilted beakers, the amorphous structures were examined using x-ray diffractometer (XRD) and microstructures were visualized with scanning electron microscopy (SEM). As a result of all the steps, a solution mixture of ethyl alcohol with a water molar ratio of 44.6: 33.9 and a starting pH of 2.3, a catalyst solution of 0.102 mol of ammonium hydroxide and a reaction temperature 30°C, were determined as optimal parameters. © 2019, Fundatia Serban Solacolu. All rights reserved.