An amazing techno-covered dream coat

Fabrics and coatings such as Gore-Tex and Teflon revolutionised the clothing industry's ability to provide waterproofing and hazard control, but very few technological advances have occurred since. However, a new technology is providing the capability to make many materials super-repellent to common factors such as water, oil, alcohol, microbes or insects. Moreover, specialised adaptations to the process can also be used to make products hydrophilic, antistatic, electrically conducting, lubricated or even fire-retardant. This novel process is based on ongoing research into plasma technology for chemical defence purposes by the UK Defence Science and Technology Laboratory (DSTL) and the University of Durham. Current protective suits are heavy and cumbersome and can lead to excessive heat stress. In addition, seams and zips need separate and costly protection from liquid ingress. The solution is to plasma-enhance entire, finished garments using this patented process so that even the zips are made highly repellent. The technology has obvious applications within the cleanroom industry, where garments must offer the maximum resistance to numerous factors, while still allowing users to perform delicate tasks in comfort. Plasma is essentially a gas created by energising molecules to a point where they become a mixture of ionised and activated atoms, molecules and electrons. The gaseous nature of plasma, and the efficiency with which it can be generated, led DSTL at Porton Down to develop a surface coating process for enhancing chemical and biological defence capabilities of military clothing. This is being further developed and commercialised by Porton Plasma Innovations (P2i).

Plasma pulses Pulses of radio frequency (RF) energy are utilised to activate a vapour of special precursor chemicals within a carefully designed chamber. These molecules polymerise and bind to the surfaces of products placed in the vessel, resulting in the surfaces gaining the properties of the deposited polymer, while leaving the inherent nature of the product unchanged. The advantage of using a plasma process to deposit polymers onto the product surface is that the precursor molecules in the plasma can get into any porous or complex object. The repellent penetrates deep into fabrics and binds to fibre surfaces at the molecular level, creating an invisible protective layer of molecular thickness. The result is a coating with a surface energy three times lower than the benchmark Teflon (PTFE). Unlike other hydrophobic treatments it is also able to repel 100% isopropylalcohol (IPA) and oils.

Incompatible factors Conventionally, when applying surface finishes to materials, costly and complex chemical formulations are required as well as high curing temperatures. This means the process can be expensive, power-hungry and time-consuming. A wide range of materials cannot be coated due to factors such as chemical incompatibility and degradation from the high curing temperatures required to effect fixation. Also, only the starting material is coated, and subsequent processing i.e. to make a garment, leaves areas such as seams and zips unprotected. P2i's plasma coating technology, though, can be used on both raw and finished materials, depositing such thin layers of polymer during processing that only tiny quantities of chemical are needed compared with traditional dipping/ curing methods. Moreover, very little of the energy used in exciting the plasma gets wasted as heat, thus the process operates at or near room temperature – very much like a fluorescent light bulb. The use of small quantities of specialised chemical precursors and the energy-efficient plasma deposition technique makes it a very environmentally friendly and safe process: the chemicals used are non-toxic and do not leach into the environment. The flexibility and inert nature of the system make the possible applications of this technology almost limitless. Efficiency, to some extent, depends on the correct chamber volume, and therefore a range of "plasma chambers" has been developed ranging from 40 to 2000 litres. The technology is highly scalable, so "off-the-shelf" and bespoke in situ chambers can be developed depending on the physical size and quantity requirements. Items as large as F1 car nose cones can be accommodated in the 2000 litre chamber, but this can also be used to bulk treat smaller items such as labcoats or filters.

Combining technologies The P2i plasma treatment processes can provide cleanroom scientists with the benefits of advanced military protection technology. Standard or specialised materials and fabrics can be treated to make them resistant to different factors depending on the environment or hazard being encountered. P2i researchers are also exploring the capability of combining coating technologies: for example, a basic garment could be given super-water repellent properties as well as being made fire retardant. Specific risks can be countered without the need for expensive and cumbersome garments, allowing cleanrooms to become much more pleasant places in which to work.