1. Nanotechnologies for Textiles, Clothing and Footwear Dr. Jimmy Lam Institute of Textiles & Clothing

2. Agenda Introduction Applications –Nano-fibres –Nano-composite fibres –Carbon nano-tubes –Nano-coated fibres Future Prospects

3. Introduction Nano is derived from the Greek word, nanos, meaning dwarf, and in SI units, the prefix nano is used as a factor indicating 10 -9. One nanometer (nm) is 0.000000001m By comparison, the diameter of single human hair is 80,000nm, and human red blood cell is 7000nm wide and a water molecule is almost 0.3nm.

4. Nano-science and nano-technology Both nano-science and nano-technology are concerned with materials that are very small. Nano-scale has generally been taken to lie from 0.2nm (atom) to 100nm. Nano-science is defined as the study of phenomena and manipulation of materials at atomic, molecular and macro-molecular scales, where the properties of materials differ markedly from those at larger scale.

5. Nano-science and nano-technology2 Nano-technologies, on the other hand, refer to the design, characterisation, production and application of structures, devices and systems, by controlling shape and size at the nano-metre scale. Nano-technologies may be considered as a range of methods of manufacturing materials along the lines of atomic assembly.

6. Nano-science and nano-technology3 Atoms, molecules and nano-sized materials are thereby manipulated in a thorough, precise and controlled manner to produce novel materials with innovative and different properties to those obtained by conventional material engineering at the micro-scale.

7. Nano-science and nano-technology4 Nano-technology has been termed a “bottom- up” technology because of the use of such small scale building units. Conventional materials engineering at the macro-scale is, by contrast, considered as a “top-down” approach. The use of nano-science and nano-technology to control the internal structure of a material at nano-scale is considered to lead to materials with fewer defects and hence of a higher quality.

8. Application of nano- technogies for textile

9. Three approaches 1.For nano-materials that are nano-scale in one dimesion, application of very thin surface coating (2nm-100nm) to textile materials. 2.Nano-fibres and nanotubes are esentially nano-scale in two dimensions and their utilization in many forms of composite materials offers opportunities for improve the mechanical properties, altering electrical, optical or biological characteristics.

10. Three approaches 3.The third approach involves the use of nano-particles (nano-scale in three dimensions) for incorporation in fibres, coating, films to provide a myriad of possibilities such as imparting antimicrobial, flame retardant and chemical softening effects to textiles and clothing.

11. Example 1: nanofibres Nano-fibres are generally taken to be fibres with a diameter less than 1μm (100nm). Electrospinning is the major fibre production method used to make nano-fibres. In this method a polymer fluid (melt or soloution) is charged with a high electrical voltage and extruded through a spinneret of 0.1-1nm in diameter, the extruded polymer jet being drawn towards an earthered collector. By manipulation of the electro-spinning conditions, micro-filaments can be produced with different diameters.

12. Electro-spinning Nano-fibres

13. Example1: nanofibres 2 Nano-fibres produced from synthetic fibre materials can be formed with a high surface area to volume ratio and small pores sizes in fabric form. The potential end uses for such nano- fibres are in filtration, wound dressings, tissue engineering, nano- composites, drug delivery devices and sensors.

14. Example2: nano-composites fibres Nano-composite fibres consist of nano- fibres containing particles with one dimension in the nano-metre range. The particles may be spheres, fibrils and by varying the amounts, their alignment, and distribution within the nano-fibre improvements in the mechanical, electrical, optical or biological properties may be obtained.

15. Nano-composite fibres

16. Example3: Carbon nano-tubes The carbon nano-tubes essentially consist of tiny shells of graphite rolled up into cylinders, either as single tubes or multiple tubes joined together. The carbon nano-tubes exhibit remarkable properties: –a tensile strength some one hundred times that of steel at one sixth of the weight. –A thermal conductivity superior to all but the purest diamond; –Electrical conductivity similar to copper but with an ability to carry much higher electrical currents.

17. Carbon Nano-tubes

18. Example4: Nano-coated fibres Nano-coating the surfaces of textiles, clothing and textiles for footwear is one approach to the production of highly effective anti-microbial treatments for killing the bacteria that can lead to malodour formation. electrical currents. The nano-coating is held on the fibre surface by strong electrostatic and hydrogen bonds and punctures the bacterial wall, killing bacteria that can accumulate in textiles and clothing through the retention of human respiration exuded through physical activity and wear.

19. Example4: Nano-coated fibres2 Nano-coating of textile fabrics, complete finished garments or shoes can be obtained by plasma polymer treatment. Plasma is the fourth state of matter (after solid, liquids and gases) which was proposed by Sir William Crookers, as a result of experiments in the passage of electricity through gases.

20. Nano-coating Plasma Treatment

21. Example4: Nano-coated fibres3 A plasma generated by electrical discharge through gas consists of a mixture of positive and negative ions, electrons, free readicals, ultraviolet radiation, and many different electronically excited molecules. By vary the conditions of the plasma treatment and the nature of the specific gas presents, a variety of surface treatments can be produced that change the chemical or physical nature of the fibre surface, thereby radically altering all treatments that depend upon fibre adhesion, eg coating, lamination and bonding.

22. Future prospects The main trust in nano-technologies applied to textiles, clothing and footwear will be to: –Improve the properties and performance of existing materials; –Develop smart and intelligent textiles with novel functions; –Greatly increase the use of fibres in technical textiles, biomedical and healthcare options; and –Open up new opportunities for fibres as sensors. Overall, nano-technologies offer great potential for the future and could radically change consumer perception of what constitutes a “standard” apparel fabric.

23. References Nano-technologies for Textile, Clothing, and Footwear by Ian Holme, Textile Magazine 2005, Vol.32, No. 1, p.7.