PFAS-Free Coatings Improve Water Repellency in Military Textiles

Lightweight, breathable, per- and polyfluoroalkyl substance (PFAS)-free textiles are key to safer, more sustainable military uniforms.

PFAS have historically been the gold standard for providing water and contaminant protection to textiles. Durable water repellent (DWR) treatments are essential for military uniforms, which undergo many weather conditions during prolonged deployments. PFAS treatments provide this protection while keeping the fabric comfortable and breathable.

Alternative PFAS-free DWR treatments must balance liquid repellency and important fabric properties, such as weight and breathability. Many current PFAS-free treatments achieve greater effectiveness by applying multiple treatment layers. This can stiffen the fabric, increase its weight, and affect its color. For tactical gear, lightweight fabric is vital, as small increases can contribute to soldier fatigue. Fabric colors must also meet military standards.

You can also read: PFAS-Free Repellent Coatings: A Safer Alternative for Textiles

Fluorine-Free Protective Textiles

A novel isopropanol, epoxy, and silica surface treatment has demonstrated high water repellency while maintaining key fabric performance characteristics. Researchers applied this treatment to untreated 50/50 Nylon/Cotton blend (NYCO) fabric. This fabric conforms to MIL-DTL-44436, the United States military specification for wind-resistant cloth.

When producing samples, researchers maintained a 3:7 weight ratio of silica and epoxy. The same authors’ 2024 study established this ratio. Though the ratio stayed the same, the sample formulations contained isopropanol content ranging from 94.8 wt% to 98.2 wt%. By adjusting the isopropanol content, researchers could assess the influence of silica and epoxy in suspension on the treated fabric.

Water Repellency

The treated fabrics demonstrated excellent water repellency across the range of solid content levels. When sprayed with treatments containing 5.2 wt% to 2.0 wt% solids, the fabrics showed complete resistance to water surface wetting. The micro- and nanoscale surface texture created by the silica particles in the treatment governs the fabric’s water repellency.

Lightweight, Breathable Fabric

Fabric weight increased directly with the solids content in the surface-treatment suspension. The 2.0 wt% suspension represents the lowest achievable weight gain while maintaining a spray rating of 100. Thus, the 2.0 wt% suspension optimizes the weight while achieving excellent water repellency.

Treatments with higher solids content also reduced air permeability and, therefore, fabric breathability. In the 2.0 wt% formulation, breathability decreased only by 10%. Researchers calculated the fabric’s color change. All samples achieved an AATCC Gray Scale for Color Change rating of Grade 4-5. This rating meets military textile specifications for colorfastness.

This treatment is a PFAS-free alternative for water-repellent fabric. It performs well while maintaining fabric color, breathability, and weight. This approach demonstrates how MIL-DTL-44436 textile standards are achievable without PFAS.