Wettability Gradient-Structured Bicomponent Polylactic Acid–Viscose Composite Fabrics with Enhanced Asymmetric Water Penetration Characteristics

Fabrics with asymmetric water penetration characteristics play an important role in our daily lives because they are often used in hygiene and medical applications. However, the existing materials have serious limitations, such as low durability and complex manufacturing processes. Herein, we report a bicomponent polylactic acid–viscose (PLA-VIS) composite fabric with a wettability gradient. The fabric can be manufactured industrially by a simple process that combines two compatible methods: needle punching and through air bonding. Five-layer cross-laid fibrous webs with various mass ratios of VIS fiber distribution were laminated in the thickness direction to produce a wettability gradient. Owing to its wettability gradient index (Rv) and porosity, the resulting composite fabric had enhanced asymmetric water penetration characteristics. Its accumulative one-way transport index (AOTI) increased from 77.8 to 165.6% as the Rv value increased from 0 to 1.5; its saturated water adsorption rate increased by 14.1 times and its water retention rate increased by 11.6 times as the porosity increased from 90 to 96%. Moreover, its water wicking performance clearly demonstrated that there was a large difference in water wetting capacity between the two sides of the fabric. The PLA-VIS composite fabric described herein has potential for use in hygiene and medical applications.