Recent Innovations in Nano-finishing in Textiles

Recent Innovations in Nano-finishing in Textiles
Disha Bhattacaharya
National Institute of Fashion Technology, Bhubaneswar, India

A review of the impacts of nanotechnology in finishing of textiles has been presented. Organized nano structures as those exhibited by fibers, nanocoatings, Nanofinishing, nanofibres and nanocompsites have immense potential to revolutionize the textile industry and open up new horizons in the field of textile finishing. This technology will provide the opportunities of different functionalities like antimicrobial, hydrophobic, dirt-repellent, flame-repellent and crease resistant properties. Value added opportunities in this field are also immense since the various attempts of different companies to commercialize the technology have been immensely successful.

Keywords: Nano-finishes, Hydrophobic, Lotus effect, Flame retardant, antimicrobial, innovation, textile modification, nanotechnology.

With the advent of nano science and technology, a new area has developed in the area of textile finishing called “Nanofinishing”. The term nano comes from the Greek word “Nanos” which means dwarf or abnormally small. If the criterion is to produce very minute particle size fibres and materials, nano technology is the only way to achieve the same. Nano technology can also be known as the technology that works at the molecular level, atom by atom to create large structures with improved molecular organization. Nanotech research efforts in textiles have mainly focused in two areas:
  • Upgrading existing functions and performances of textile materials.
  • Developing intelligent textiles with completely new characteristics and functions.
The most significant impetuous to the development of nanofinishes in textiles has been given by the dedicated work of Taiwan born Dr. David Soane. Through his experiment he devised ways to use nanotechnology to add unusual properties to synthetic textiles without changing the fabrics look or feel. Another pioneering work in this field was done by Prof. W Barthlott of Bonn, Germany. His work involved the understanding of hydrophobicity and self cleaning properties of a lotus leaf and how it can be applied in textiles. This research was the basis on which water and oil repellent textile finishes have been invented by Schoeller Textiles, Switzerland. The most recent development in the field of Nanofinishing was developed by Dr. Walid Daoud and Dr. John Xing of the Hong Kong polytechnic university. These scientists devised an efficient way of coating cotton with tiny particles of titanium dioxide which get triggered by sunlight and make the fabric self cleaning against dirt, environmental pollutants and harmful micro organisms. Silver-containing antimicrobials have been incorporated into wound care devices are rapidly gaining acceptance in the medical industry. Once absorbed the silver ions kill microbes, resulting in treatment of infected wounds or the prevention of infection in at-risk wounds. In SilverlonTM, manufactured by Argentum, nanosilver produced by the reduction of silver nitrate is deposited on sensitized nylon fibres. The silver laden polyamide fibres are then attached to a fabric.

Nanotechnology has opened immense possibilities in textile finishing area resulting in to innovative new finishes as well as new application techniques. Particular emphasis is on making chemical finishing more controllable, durable and significantly enhance the functionality by incorporating various nanoparticles or creating nanostructured surface. Nano finishes are generally applied in nonemulsion formehich enables a more thorough even and precise application on textile surface. They are generally emulsified into either nanomicelles, made into nanosols or wrapped in nanocapsules that can adhere to textile substrates easily and more uniformly. Since nano particles have a large surface area to volume ratio and high surface energy, they have better affinity for fabrics. Therefore these finishes are more durable, effective and do not adversely affect the original handle or breathability of the fabric.

The different types of finishes in Nano finishing technology include the following:
  • Hydrophobic nano finish: Fluorocarbon finish is one of the most important nanofinishes applied to textiles. Fluorocarbons are a class of organic chemicals that contain perfluoroalkyl residue in which all the hydrogen atoms have been replaced by Fluorine. These chemicals have very high thermal stability and low reactivity which reduce the surface tension therefore making the fabric hydrophobic in nature. The attached multifunctional molecule can impart wrinkle resistance by cross linking cellulose chains and also impart water-repellancy, crease resistance, soil resistance, detergent free washing, increased speed od drying, etc. The durability of this finish is much better than the conventional fluorocarbon acrylate polymer based finish. 
Lotus leaf effect and SEM imagery
  • Anti-microbial Finish: Silver ions have broad spectrum of antimicrobial activities. The method of producing durable silver containing anti microbial finish is to encapsulate a silver compound or nano particle with a fibre reactive polymer. Prof. Yang has patented a process for preparing silver nano particle containing functional microcapsule having the intrinsic or therapeutic properties of silver. 
  • Photo-catalytic self cleaning: Advanced orientation processes that are combination of powerful oxidizing agents with UV or near UV light have been used to remove organic pollutants from textiles. TiO2 has been proved to be an excellent catalyst in photo degradation of colorants and other organic compounds. Nano sized TiO2 particles show high photocatalytic activities because they have a large surface area per unit mass and volume as well. 
SEM images of (a) uncoated cotton fiber, (b) titania coated cotton fiber showing the morphological change in the surface structure, (c) higher magnification image of titania coated cotton fiber showing the shape and size of the titania particles, and (d) higher magnification image of a titania film coated on glass.
  • Anti pollen finish: Miyuki Keori Co of Japan is marketing anti pollen garments or fabrics. The smoothness of the finish on the surface and the anti-static effect does not let pollen or dust come close. This is achieved by using the polymer which has anti static or electro conductive composition. 
  • Flame retardant finish: Nyacoll nano technologies. Inc has been the world‟s largest supplier of colloidal antimony peroxide which is used for flame retardant finish in textiles. Nano antimony pentoxide is used with halogenated flame-retardants for a flame retardant finish. 
  • Odour repellent finish: A Talwanese nanotech firm Greensheild has created underwear that fights odour which is achieved through nanotechnology. Negative ions create a magnetic field that inhibits the reproduction of odour causing bacteria. 
  • UV protection: Nano clay particles of montnorblonite is one of the most commonly used UV blocker. It also increases 40% tensile strength and 60% flexural strength.
Nano particles has thus emerged as the „key‟ technology which has revitalized the material science and thus has immense potential for development and evolution of a new range of improved materials including polymers and textiles. However there are many challenges in the development of these products which needs to be intensively researched so that the wide range of application envisaged can become a commercial reality. An excellent dispersion and stabilization of the nano particles in the polymer matrix is crucial to achieve desired nano effects. To conclude, nano technology definitely has the potential to being a revolution in the field of technical textiles.

  1. M. Joshi and A. Bhattacharyya (2011) Nanotechnology: A New Route to high performance and functional textiles
  2. Nano finishing of textiles: Aravin Prince. P & Raja.P
  3. Nano finishes: M.L Gujaran


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