Study On The Preparation Of Superhydrophobic Cotton Fabrics By The Low Pressure Plasma-induced Graft Polymerization

Cotton textiles are applied widely in clothing material due to their excellent bulk properties, such as softness, comfort and biodegradability. However, the cotton fabric is easily soaked and stained by liquids due to the abundant hydroxyl groups on its surface. For that reason, there is a strong demand to tailor their surface properties for specific applications. Many traditional methods have been designed to prepare hydrophobic cotton fabrics, such as sol-gel, chemical vapor deposition, and layer-by-layer assembly technique. Along with saving water resources and reducing energy consumption in finishing of textiles, some novel technology and methods to fabricate hydrophobic fabrics have come into being. But the method of plasma-induced graft polymerization is an efficient and friendly technology, which have concerned by researchers.In this paper, superhydrophobic fabrics were successfully prepared by low-voltage radio frequency glow discharge plasma-induced graft polymerization with unsaturated cyclic silicone monomer and linear ester monomer onto the cotton fabric substrates. The main contents are as follows:（1） A facile and cost-effective method to construct fluorine-free superhydrophobic films on cotton fabric substrates was described in this chapter. The superhydrophobic films were fabricated by immersing cotton fabrics in the monomer solution of 1, 3, 5, 7-tetravinyl-1, 3, 5, 7-tetramethylcyclotetrasiloxane(D4^Vi) and followed by the treatment of the air low temperature plasma with glow discharge at the pressure of 10 Pa. The cotton fabric before and after the plasma treatment were characterized by using field emission scanning electron microscopy, infrared spectroscopic analysis, X-ray photoelectron spectroscopy, energy-dispersive spectrometry and thermogravimetric analysis. The wetting behavior of cotton fabric was evaluated by the water contact angle measurement. The results showed that the polymer films coating on the cotton fibers were constructed by the plasma inducing graft polymerization with D4 Vi and the glow discharge power and time of low-temperature plasma were critical for D4 Vi graft polymerization on the cotton fabric. Moreover, the treated cotton fabric demonstrated extraordinary water repellency with water contact angle more than 150° for a 5 u L water droplet under the condition of 5 min and 100 W. The study confirmed annular siloxane and vinyl groups of D4 Vi were broke and polymerized by the low-temperature plasma glow discharge, and formed high molecular polymer deposited on cotton fabrics finally.（2） Helium plasma inducing graft polymerization of 1, 3, 5, 7-tetravinyl-1, 3, 5, 7-tetramethylcyclotetrasiloxane was investigated on cotton fabrics to prepare hydrophobic materials. The effects of plasma treatment parameters, such as radio frequency power, treatment pressure and time on the graft ratio were investigated. The results showed that the treated cotton fibers were coated by uniform, dense films which perform and cotton fabric presents an excellent hydrophobicity with a water contact angle of 150° under a load pressure of 20 Pa, radio frequency power of 80 W and time of 2 min. The cotton fabrics have better washing fastness as the treated cotton fabrics have higher grafting yield. Meanwhile, the influence of plasma etching on deposited polymers become weaker with the Helium instead of air gas.（3） In the one-step process, the cotton fabric pre-impregnated with the monomer solution of stearyl methacrylate（SMA） was placed in the plasma chamber and followed by glow discharge of the Helium low temperature plasma. The results showed that polymer films could be coated on the cotton fibers through the plasma induced grafting polymerization of SMA. The modified cotton fabrics exhibited an extraordinary hydrophobicity with a contact angle of 149° for a 5 μL water droplet and excellent thermal stability. The hydrophobic polymeric films are formed due to the unsaturated acrylate groups of SMA could undergo polymerization by the Helium plasma glow discharge. The relative hand value and mechanical breaking strength of the cotton fabrics declined slightly after graft polymerization of SMA by the plasma.