There are many innovative textile materials and fabrics being developed by textile scientists and technologists. Wouldn't it be wonderful if a garment one is wearing could stay clean without having to wash it for a few days? This would definitely save the cost of cleaning the fabric or garment and also increase the longevity of the textile. Keeping water and dirt at bay has been a quest of many textile innovators for years now.
Today, the textile industry has more than one technique of developing self-cleaning textiles. With help of nanotechnology and multipurpose chemical finishes to design self-cleaning cloths. There are various ways of achieving the self-cleaning effect in fabrics. One of them is biomimicry in textiles, which has led to the development of water and dirt resistant finishes. The concept is inspired from the lotus leaves that have the wicking properties to keep the surface clean. Using nanotechnology a fabric has been developed that not only keeps the exterior clean but also prevents the textile material from being contaminated and bacteria-free.
There are basically two different types of self-cleaning coatings: Hydrophilic and Hydrophobic coats. The lotus effect is achieved with a hydrophobic coating, which have high water contact angles, above 90 degrees. The contact angle is determined by evaluating the chemical and topographical qualities of the surface. Superhydrophobic coating have a water contact angle of greater than 150 degree. The water droplets from such surfaces form a spherical shape and roll away from the surface carrying all the dirt away.
Nano particles used in the coating have a large surface area to volume ratio and posses high surface energy. This makes particles have better affinity to fabrics, which ultimately makes the functional coating last longer. This has led to extensive research and growth in the use of nanotechnology. Today, there are textiles that repel not just water and dirt, but also can keep wine and coffee stains, bacteria, and odour away.
One of the techniques while using nano particles for coating is by using photocatalysts, wherein a mixture of titanium dioxide and zinc oxide act as self-cleaning and anti-bacterial agents. A thin coating of titanium dioxide particles which measure just 20 nanometers in diameter is treated over the fabric. The surface of the textile material when exposed to light breaks down the impurities such as dirt, pollutants, and micro-organisms that come in contact with the fabric into carbon dioxide and oxygen. This leaves the surface free from all sorts of stains and impurities.
Another method utilizes microwaves to do so. A chemical that can repel the dirt and oil is used to coat the surface creating a protective layer using nano particles. This technology is used to make uniforms and innerwear for defense personnel. These kinds of coating have the ability to keep bacteria at bay and the cloth hygienic for days.
Silver also possesses a quality to repel dirt and keep bacteria away. Silver injected nano particles used as coatings, can be beneficial to produce self-cleaning fabrics. Silver is also assumed to have healing properties and hence used in garments like socks. Another chemical used to obtain self-cleaning properties is chlorine. It is used in the form of molecules that consist of halamines, which have no adverse effects unlike chlorine in gas form. Chlorine halamines is adhered to cellulose fibres of cotton and after a few washes, the fabric is again treated with chlorine bleach to regain its cleaning properties. Such a treatment is used in medical textiles like wipes, beddings, and towels.
Self-cleaning garments and fabrics retain the original texture and feel of the fabric without bringing about any change. Clothes that can keep clean can save a lot of water and energy by preventing frequent wash. Using above mentioned technologies self-cleaning fabrics can prevent dirt, oil, and also act as a disinfectant. The methods used for developing self-cleaning fabrics keeps the textiles long lasting and fresh looking than ordinary fabrics.
Anti-dirt and self cleaning clothes can be used in medical, sports, defense, and home textiles widely. However, there are a few shortcomings in some of the techniques used. The breaking down process of impurities is time consuming and depends on the amount of dirt or stains to be cleaned. The electrons in the titanium dioxide react with oxygen using light energy. In order to break down completely a large stain from a fabric, it will have to be exposed to sunlight for more time. Also, developing hydrophobic textile materials is not only time taking but also expensive.
Refining the technologies for self-cleaning fabrics and garments will help decrease the cost and also have a long-lasting effect of the nano-particles used. This environmentally friendly solution can help saving dry cleaning and laundry bills, energy, and time. One can expect in the near future garments that have self-cleaning features available commercially at stores too.