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Fluorine-free WPU coating delivers durable water repellency
A new fluorine-free water-borne polyurethane coating combines side-chain functionalisation with dual-siloxane synergy to deliver durable water repellency on textiles. The system avoids bio-toxic fluorides and volatile organic compounds while remaining compatible with conventional pad-dry-cure finishing processes.
The widespread use of functional water-repellent textiles has so far been limited by their reliance on bio-toxic fluorinated compounds or complex processing routes, raising both environmental and economic concerns. Addressing this gap, researchers have developed a fluorine-free, water-borne polyurethane (WPU) coating that delivers effective water repellency through a combination of side-chain functionalisation and siloxane synergy.
In the new design, unconstrained pendant tertiary amine groups were introduced to support efficient amine ionisation and to enhance emulsion stability. Building on this foundation, the researchers polymerised a WPU system containing polysiloxanes on both the backbone and the mobile side chains, enabling stable PDMS loading within the formulation.
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Dual-siloxane barrier with proven durability
The dual-siloxane architecture creates a reinforced water-repellent barrier with two complementary mechanisms. Mobile siloxane chains repel liquid water, while soft-segment siloxanes coat the fibre surface to provide an isolating layer. Cotton fabrics treated with the optimised WPU-I8P6 working solution achieved a water contact angle of 148.0° and scored 90 in the spray test according to AATCC Test Method 22–2017.
Application-oriented tests confirmed strong durability of the finish: water repellency was retained after 360 h of weathering, 50 abrasion cycles, washing and chemical corrosion. As the fluorine- and VOC-free emulsions can be processed using a straightforward pad-dry-cure finishing route, the authors describe the approach as a sustainable and industrially viable strategy for producing functional water-repellent textiles.
Source: Wang, S. et al., Fluorine-free waterborne polyurethane coatings with siloxane synergy for sustainable water-repellent textiles. Progress in Organic Coatings (2026).
