Jinlong Yao

Synthesis and characterization of photoreactive silica nanoparticles for super-hydrophobic cotton fabrics application

In this research, a novel method was developed to improve the super-hydrophobic stability of cotton fabrics without affecting the washing ability. The cotton fabrics were treated with hybrid photoreactive silica nanoparticles (denoted as silica-N3) and hexadecyltrimethoxysilane under ultraviolet light. Silica nanoparticles were synthesized by grafting an azido group onto silica and confirmed by proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance and Fourier transform infrared spectroscopy. Untreated and treated cotton fabrics were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. Wettability was investigated by water contact angle (WCA) and water shedding angle (WSA). Moreover, the super-hydrophobic durability of coated cotton fabrics was evaluated by washing tests. The results showed that the treated cotton fabrics exhibited excellent chemical stability and outstanding non-wettability with a WCA of 154.9° for a 5u2009µL water droplet and a WSA of 8.7° for a 15u2009µL water droplet. In addition, the super-hydrophobic cotton fabric showed excellent washing durability. After 30 cycles, the contact angle was still larger than 135°.

Superhydrophobic organosilicon-based coating system by a novel ultravoilet-curable method

A robust superhydrophobic organosilica sol-gel-based coating on a cotton fabric substrate was successfully fabricated via a cost-effective one-step method. The coating was prepared by modification of silica nanoparticles with siloxane having long alkyl chain that allow to reduce surface energy. The coating on cotton fabric exhibited water contact angle of 151.6°. The surface morphology was evaluated by scanning electron microscopy, and surface chemical composition was measured with X-ray photoelectron spectroscopy. Results showed the enhanced superhydrophobicity that was attributed to the synergistic effect of roughness created by the random distribution of silica nanoparticles and the low surface energy imparted of long-chain alkane siloxane. In addition, the coating also showed excellent durability against washing treatments. Even after washed for 30 times, the specimen still had a water contact angle of 130°, indicating an obvious water-repellent property. With this outstanding property, the robust superhydrophobic coating exhibited a prospective application in textiles and plastics.