TEOS based water repellent silica films obtained by a co-precursor sol–gel method

Abstract

The nature of interfaces between water and hydrophobic materials has been a subject of great interest. Experimental results from tetraethoxysilane (TEOS) based hydrophobic silica films synthesized by the two step sol–gel process using hexadecyltrimethoxysilane (HDTMS) as a co-precursor are described. The molar ratio of TEOS, methanol (MeOH), acidic water (0.001 M, oxalic acid), and basic water (8 M, NH4OH) was kept constant at 1:66.66:6.76:6.66, and the molar ratio of HDTMS/TEOS (M) was varied from 0 to 22.9 × 10−2. The maximum contact angle of 125° was obtained for M = 22.9 × 10−2. It is observed that the water contact angle value on the HDTMS modified films remained stable at 125°, after heat treatment up to 235 °C. However, the water contact angle value decreased to 52° in the case of unmodified films, indicating the improvement in the thermal stability using HDTMS as a co-precursor. The hydrophobic silica films retained their hydrophobicity up to a temperature of 235 °C and above this temperature the films became hydrophilic. The hydrophobic silica films were characterized by surface roughness studies, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, and % optical transmission.

Thermal stability and flame retardancy of polyester, cotton, and relative blend textile fabrics subjected to sol–gel treatments

“…The sol–gel process5,15,19–26 is a relatively novel process in the textile field when applied to impart such properties as flame retardancy, thermal stability, hydrophobicity, and antistaticity. By this technique, it is possible to induce the formation of a homogeneous coating of (nano)particles directly on the textile fabrics.…”

Porous superhydrophobic silica films by sol–gel process

“…Many scientists have made impressive efforts for the fabrication and understanding of superhydrophobic surfaces. Several technological approaches to altering the wettingto-dewetting transition have been explored [4][5][6][7][8][9]. Technologies related to water repellent coatings are important for suppressing chemical reactions and bonding formations between water and solid surfaces.…”

Modification of Surface Energy and Wetting of Textile Fibers

“…Roughened surfaces have commonly been obtained by the introduction of nano-size particles onto the pristine surface, and the sol-gel technique has been reported as a promising tool for the preparation of water-repellent coatings that is especially versatile for applications on glass, paper, and textile [95][96][97][98][99][100]. An exhaustive review on the application of sol-gel techniques to textiles has been published by Mahltig and Textor [101], and a series of selected articles is reported in Table 7.…”