Green and Scalable Fabrication of Nonwoven Composites Featured with Anisotropic Water Penetration

Abstract

Nonwovens with anisotropic water-penetration properties are of significant academic and practical importance. However, existing materials suffer from inherent limitations, because of which the use of chemicals is inevitable and the proportion of hydrophobic contents is largely confined. Herein, we report for the first time, the chemical-free and large-scale fabrication of nonwoven composites having anisotropic water-penetration features. A layer of chitosan (hydrophobic) fibers is consolidated with a layer of viscose (hydrophilic) fibers via the hydroentanglement technique. The high-pressure water jets from hydroentanglement achieve the vertical movement of fibers, thus generating a gradient fiber distribution across nonwoven thickness. This gradient fiber distribution enables fast water-penetration from the hydrophobic side, even when 90% of the fibers are hydrophobic and the hydrophobic layer exceeds a record-high thickness of 1.6 mm. Versatility of our method is further demonstrated by realizing simila...