Durable Water Repellent (DWR) Finishing
topic
DWR finishes reduce surface energy to <20 mN/m, causing water contact angle >130° (hydrophobic surface, Cassie–Baxter wetting state). Traditional C8-fluorocarbon (PFOA/PFOS-based) DWR provides excellent oil and water repellency; now restricted (REACH, EPA) due to persistence. C6-fluorocarbons (shorter chain, less persistent) have reduced oil repellency. Fluorine-free DWR alternatives: wax emulsions, silicone, dendrimer-based, PFC-free polyurethane. Durability assessed by spray test (ISO 4920) and wash durability (50 washes).
Role
DWR finishing is central to outdoor and sportswear performance. The transition from fluorocarbon to fluorine-free DWR is a major current challenge in sustainable textile chemistry, making this topic highly relevant academically and industrially.