Comparisonal studies of surface modification reaction using various silylating agents for silica aerogel

Abstract 

Surface modification is one of the important steps for synthesizing hydrophobic silica aerogels by ambient pressure drying in which silylating agent plays a vital role. Trimethylchlorosilane and many kinds of methoxysilanes like trimethylmethoxysilane, dimethyldimethoxysilane, and methyltrimethoxysilane have been used as the silylating agents. In this work, silylation effects were investigated with different molar ratios of silylating agent/n-hexane mixture. In addition, the mechanism of the silylation reaction is explained based on the molecular structures by considering the number of methoxy/ methyl groups. The silylation extent was characterized by using optical imaging, bulk density and porosity analyses, Fouriertransform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, and contact angle measurements. It has been found that the methoxysilane-based silylating agents can be used as a replacement without producing the harmful hydrochloric acid and retaining the similar tendency to trimethylchlorosilane in surface modification. This research approach seeks to an alternative silylating agent by investigating the impact on the surface modification based on the molecular structural parameters and reaction mechanisms.

paper information
(2020) Journal of Sol-Gel Science and Technology, 96, DOI: 10.1007/s10971-020-05399-5
Authors: Ha-Yoon Nah, Younghun Kim, Taehee Kim, Kyu-Yeon Lee, Vinayak G Parale, Chang-Hyun Lim, Ji-Yeon Seo, Hyung-Ho Park, Juwon Oh

DOI : https://doi.org/10.1007/s10971-020-05399-5