How to manufacture textiles with nanotechnology?
How to manufacture nanotechnology textiles is the third post in the series nanotechnology in the fashion industry and will discuss how nanotechnology is applied to textile fibres. One of the most important and advanced parts of developing garments is called surface design. A considerable amount of research is taking place in the field of surface modification of textiles with a view to improving properties and processes. Nevertheless, most conventional methods such as wet processing of textiles are often harmful to the environment and also resource demanding especially when it comes to watering. In the future such processes will probably not be accepted by neither consumer, green organizations nor brands due to the growing concerns for global warming and demand for environmental friendly consumer products. Nanotechnology was first applied to fabrics by a former polymer chemist Dr David Soane around 1998 when his team managed to replicate the natural water-repellency of plant surfaces and animal coats. The company is known as Nanotex. Other achievable new function’s nanotechnology can provide:
- flame resistance
- self-cleaning capability
- modifiable colour
- UV protective
- Heat reductive
- water repellent
Nanotechnology cannot exist without Nanoscience
At the nanoscale material properties can behave very different, unexpected or even in a novel way than at macro scale, this is the core and the most fundamental learning. Nanotechnology is characterized by design, manufacture (synthesis) and application of nanomaterials and nanostructures in advanced macro- and micro-systems. The core of science innovation is happening with structures and materials from a sub-atom metre to many micrometres (hundreds of nanometres).
Nanometrology of surfaces
Nanotechnology measurement tools and future standardization methods are under pressure as demands for extremely precise and new ways to measure material phenomena at nanoscale is required for Successful implementation of nanotechnology. One of the important developments that are simultaneously happening is the ultra-important nanometrology tool scanning probe microscope (SPM) or preferably called nanoscope (Ultra-microscope). Nanoscope makes it possible further develop nanomanufacturing in the direction of bottom-up and self-assemble techniques in production of nanomaterials.
Nano-textiles are basically fibrous structures with nanofibers, nanomaterials and nanofinishes incorporated into them by various methods. These nanomaterials serve as the foundation for developing higher-order structures such as fabrics and composites. Usually, nanotechnologies in textiles are classified into:
- non-functionalized textile products
- functionalized and finished textiles
What is nanomaterials?
Nanomaterials are generally characterized as materials with dimensions of 100 nm or less, in one or two directions of the material. At such small scales (and particularly less than 10 nanometres) fibre morphology, chemistry and other materials are not independent of nanoscales. Many factors such as at material surface roughness, texture, and how its cut may actually produce very different and unforeseen results implementing nanotechnology. Therefore, an improved and more dynamic measurement methology is likely to become increasingly valuable, time-saving and as the process together with material structure as an integrated part of nanometrology. Nanometrology of textile fibre morphology, surface design and interactions applying nanomaterials by various methods such as coating, electro-spinning, sprays are extremely challenging due to its complexity and therefore, in many cases require completely different approaches. Nanomaterials may be fabricated from multiple substances where each presents a set of unique properties and domains such as shape, structure, geometry, surface size and topography.
Fibre morphology and surface modification of textiles
Nanofabrication involves a wide range of surface modification procedures that are important in many different areas. The key for successful nanofabrication of textiles depends increasingly on fibre morphology and research into textile surface properties. The main reason for applying nanotechnology in surface modification for textile applications is that nanomaterials can give brand-new dimension to textiles by having multi-functionality. Since the surface modification of textiles in aqueous solutions touches almost all important sectors in the textile industry, surface modification research and the textile industry basically shares the market trends and innovations. Modification of the surface to improve the properties of fibres is a tremendous growth sector within textile development now and the next years ahead, and the growing use of nanotechnology in modifications will furthermore expand this field. This fast progression of many aspects of science and technology into the nanoscale realm, therefore, inherently results in the greater importance of surfaces in determining the behaviour of nanoscale devices and material phenomena. See also Fibre morphology in the Eco Fashion Dictionary.
Surface modifications of textiles
Textile surface modification and fibre morphology plays and significantly important part when adding nanomaterials into textiles, fibre morphology; one thing is the need for acceptable strength and fibre stability in order to be useful. Nevertheless, the basic requirements for fibre used in textiles are fineness and length. In general, the most well-known type of fibre is usually -categorized into four groups depending on their properties: Textile surface design in the Eco Fashion Dictionary.
In addition, and more importantly several fibres got thermal, biological and other advanced properties that are used in various applications such as medical textiles, smart textiles, protective applications etc. Other issues can be significantly important when incorporating nanomaterials are fibre form, surface hairiness, dyeability and moisture absorption, in spite of well-known is the consequence of geometry that the surface/volume ratio of an object increases as the object becomes smaller.
The relationship between fibre and its ability to absorb moisture is useful for clothing comfort or even more important if non-absorbing. Absorbed moisture also supports electrical conductivity and disperses static electricity, which alternatively demand the use of anti-static finishes. When self-cleaning textile was developed based on the “lotus effect, the basic correlation between textile constructions, surface topographies and wetting behavior after water-repelling functional was understood. Earlier research, for example, shown that the wetting behavior is considerably impacted by topography, which results from weave and type of yarn.
Yarn type such as filament yarn or staple fiber decides the extent to which water drops roll off textiles. It is well-known that long, protruding fibers, such as occur with escalating regularity in ring yarn samples, prevent water drops from rolling off. High fibre density of short protruding fibre such as in the case of nonwovens, promote rolling off simply because they present a smaller surface area to the water drops. Therefore, self-cleaning fibre is determined by the ability of water drops to access dirt particles. Thus, good water-repellent behavior, which results from the hairiness of the sample, does not automatically guarantee excellent self-cleaning behavior, more on self-cleaning later in the post and next).
Manufacturing of nanotechnology textiles
In order to manufacture nanotechnology textiles, nanomaterials need to be mixed into the fibre structure. There are several ways to integrate nanoscale controlled properties into textiles, for example, incorporation of nanomaterials into fibres on fabric surface level or give the fibre itself a nanoscale by novel ways of fibre spinning. These new methods make it possible to spin fibre with a diameter between 20 and 500 nanometres. This is 10-500 times thinner than traditional spinning technology. A lot of innovative ways to make textiles lies outside what is regarded as nanotechnology since the fibre diameter between 100-500 nanometre, however, most books on nanotechnology textiles include such research of nanofibres.
Surface modification of textiles with nanomaterials is the easiest and simplest strategy to integrate into already operative fabric manufacturing technology. There are a number of different ways to approach and apply nanomaterials via the surface of textiles, such as coating, electrostatic or impregnate; for example, textiles with pre-treated water (nanoparticles dispersion in water). The Australian company NanoShield has developed zincoxide nanoparticles in water to be incorporated into fabrics or nonwoven substrates through coating with textile properties such as UV blocking, anti-microbial, and anti-inflammatory. Another example is the self-cleaning fabrics developed bySchoeller that manage a modification of the fabric surface to mimic the surface structure of lotus leaves using silica nanoparticles.
Nanotechnology and multi-functional properties
The advantage of adding nanotechnology to create multi-functional properties to the base substrate is obvious. For example, nanoparticles of palladium and Platinum imparts catalytic properties such as decomposition of harmful gases or toxic industrial chemicals. However, mostly these nanomaterials are impregnated onto textile materials without noticeable affecting texture. Furthermore, metal nanoparticles presence of surface plasmons adds a beneficial advantage of optical extinctions, that create different colours depending on shape and size of the particles, this is also known as structural colours and will be presented in the next post as a part biomimetics, looking at nanoscale structures used by animals, insects and plants (for example, example the Lotus effect, Morpho butterfly structural colours).
Methods for Surface Modification
Surface modification process for textiles with or without use of nanotechnology can be divided into two main categories:
- physical process – for example, use of lasers, plasmas, temperature, ball-milling, polishing and grinding to modify the material
- chemical process – use of chemicals to introduce new properties such as surface energy or density different from the bulk material
A few methods for adding nanotechnology to textile fibre
- Layer-by-layer( LbL) technique
- Liquid phase deposition (LPD)
- Langmuir–Blodgett (LB) films
- sol-gel technique
- plasma techniques
- chemical vapor deposition
- physical vapor deposition
- Laser techniques
Nanotechnology overcomes the limitations of conventional methods when imparting various functional properties to textile materials. Those functional properties are of the highest importance, and give noticeable improvements in the wear comfort and care. Despite great research effort into the nanofinishing of textiles, their commercial exploitation has only just begun. The main emphasis in the application of nanotechnologies to textiles will be to:
- improve the properties and performance of existing materials
- develop smart and intelligent textiles with novel functions
- increase the use of fibres in technical textiles, biomedical textiles and health-care applications
- use of fibres as sensors