Hydrophobic Material: Effect of Alkyl Chain Length on the Surface Roughness

Abstract

The clean technologies of self-cleaning surfaces are expanding rapidly. Highly hydrophobic coatings with strong adhesion, high durability, and dirt-free surfaces have been prepared via sol-gel deposition of SiO2-TiO2-alkylsilane. The influence of the effects of the alkyl chain length of silane on surface roughness was investigated. This deposition involved a one-layer technique to produce the rough surfaces. The bimetal oxide of SiO2-TiO2 created a high level of surface roughness. As a result, the water contact angle of the coatings increased with the increasing alkyl chain length of silane (up to C=8). However, the water contact angle decreased when the C=16 of alkylsilane was applied. It was predicted that the longer alkyl chain would cause the molecules to collapse. The higher hydrophobicity was produced by SiO2-TiO2-OTMS coatings with a water contact angle of about 140.67 ± 1.23°. The effect of the dip-coating technique (one layer and layer-by-layer) on hydrophobicity was also discussed. The results showed that coatings produced by the one-layer technique had a higher contact angle than coatings made by the layer-by-layer technique. The coatings were stable under outdoor exposure and able to hinder dirt attachment to their surfaces.

Study on the Hydrophobicity and Antibacterial Activity of Silica Sol-Chitosan-HDTMS Treated Cotton Fabric Dipped in an Aquas Media

“…This is supported by earlier studies, which reported that the contact angle decreased after 25 to 30 washings, and the reduction may be due to cracks in silica film on the fibre surface caused by the swelling of cotton [33,47]. The second reason is the absorption of water molecules by OH groups present on the coated surface during long-term direct contact with water [41,42]. Furthermore, any material intended for use as a biomaterial must be biocompatible and must also have a contact angle greater than 120° for at least a week after implantation in order to stop this tissue reaction [13,17].…”

“…In water, hydrogen bonds break easily [40]. In addition, the unreacted OH group present on surface of coated fabric may absorb water molecules physically or by hydrogen bond [41,43]. Additionally, the spectra between 1600 cm −1 and 1700 cm −1 appeared for the sample dipped for 30 days, while the peak between 1600 cm −1 and 1700 cm −1 normally appeared for amine groups [34].…”

Synthesis and characterization of silica gel from Lapindo volcanic mud with ethanol as a cosolvent for desiccant applications

“…26 The absorption band at 1640 cm −1 is associated to the -OH absorbed on the silica gel surface, which is supported with the board peak at 3600-3400 cm −1 . 27 Increasing the volume of ethanol led to an increase in the intensity of the Si-O-H vibration at 960 cm −1 , demonstrating that the presence of ethanol promotes the hydrolysis process in the reaction. Compared with the IR spectra of LM, the intensity of absorption band at 960 cm −1 of the synthesized silica gel is broader, revealing the formation of the amorphous silica phase.…”

Crosslinked siloxane–silsesquioxane elastomer with pyrene functionalization for rapid adsorption of benzene, toluene, and xylene (BTX) from water and sensing of charged species

“…Py-CSSE demonstrates a shorter D 1 -spacing than CSSE (0.81 nm vs. 0.98 nm), indicating that the incorporation of pyrenyl moieties into Py-CSSE probably prevents the formation of long siloxane chains between each silsesquioxane unit during polymerization and potentially causes a collapsed structure as a result of the self-assembly disorder, resulting in a lower hydrophobicity. 63 The energy dispersive X-ray (EDX) pattern showed the presence of Si, O, and C atoms which can imply the presence of both the SQ cage and pyrene aromatic ring within the polymeric networks (Fig. S11 †).…”