At University of Leeds, how much of the research on DWR is in collaboration with industry? What sources of funding have supported your research?
There are many organisations, chemical companies and brands who are researching alternative repellent finishes, and there are many areas of this topic which require further research. Stefan is a researcher at Swerea and can say more on their work. The academic research at the University of Leeds is looking at post consumer care of repellent fabrics in outdoor apparel, working alongside outdoor brands – it is a PhD project. We are all contributing to the knowledge on fluorine and fluorine-free repellent treatments in the hope that alternative chemistries can give adequate functionality throughout the products use-phase.
Great question. To me this is all about product design. To be sure, this work is going on. Like so many products of the industrial age, it’s really hard to reinvent entire supply chains based on processes that are decades if not centuries old. It’s also hard to innovate on one operation in a complex manufacturing chain. Bringing new products and processes to commercial reality and scale remains a challenge. Viva the disruptive innovators!
Lots of non-fluorinated technologies are in commercial use today and it looks like many are in the pipeline. Some are said by their suppliers to be based on renewable materials (bio-based). All need to be carefully assessed for their potential hazards to workers, the environment and consumers. Hazard testing regimes are an integral part of good product stewardship.
DWRs refers to the general class of Durable Water Repellents, including fluorine chemistry but also silicone chemistry and hydrocarbon chemistry. Fluorine is used for repellent finishing as it provides repellency to such a wide range of liquids, from oil-based to water, and has unrivalled properties. In some instances this is necessary, for example in technical textiles such as firefighters clothing. However fluorine chemistry has been applied to a wide range of consumer apparel for stain repellency as well as water repellency, this is marketed as an ‘easy-care’ finish. In some cases, the necessary functionality is being reassessed by manufacturers to see if alternative DWRS will provide the adequate repellency.
Test methods are tailored to reflect the actual use of the DWR treated article. The washing, abrasion etc. tests are set up to reflect consumer use. Typical DWR water repellent performance specifications call for an 80 spray rating after 20 launderings. The AATCC tests are the most widely used.
As far as we know from scientific studies there is probably degradation from the highly fluorinated side chain polymers at are
actually the DWR treatment "layers" and/or impurities of precursors e.g telomeralcohols that are either emitted themselves or oxidized into
perfluorinated acids e.g PFOA. The other part of your question are possible pathways. For pefluorinated acids such as PFOA these substances are transported through the environmental water systems and eventually end up in the food chain and in our drinking water. There are several studies available today that at least tries to describe these mechanisms and our research is one of them. It is complex but we know today that the oxidation of the so called telomer alchols and related precursors are oxidized in environment (new data indicate even during use) into perfluorinated acids
The University of Leeds is one individual PhD project, which has been self-directed and has been funded by the University only. I have made many contacts with the industry who have been very supportive of my PhD research, and its direction, but there is not a direct collaboration with industry yet.
The central driver is the performance needed for the article in its use. Workwear may need water and oil repellency as well as stain release. An umbrella may just need water repellency. The stain resistance is manifested in the repellency and in specific cases, stain release, where stains soak in but are easily laundered to remove the stain.