Micro–Nanofiber Three-Dimensional Antibacterial Sponge with Wetting/Pore Dual Gradient for Rapid Liquid Infiltration and Uniform Retention in Diapers

The core layer of disposable diapers typically contains a blend of superabsorbent polymer (SAP) and pulp, resulting in slow liquid absorption, layer separation, reverse osmosis, and potential skin issues owing to the addition of antibacterial agents to the surface layer. Therefore, a core layer with rapid liquid absorption, uniform retention, and antibacterial properties must be developed to improve wearer comfort. In this study, a three-dimensional network porous structure for the core layer of a disposable diaper was prepared by solution blow spinning (SBS). This structure comprised a superabsorbent fiber (SAF) and hydrolyzed polyacrylonitrile (HPAN) micro/nanofibers with a dual gradient in wetting/pore size. Progressively increasing the SAF content in each layer to incrementally increase wettability and controlling fiber diameter, a gradient pore structure with sizes of approximately 30 μm-16 μm-7 μm was formed. This design exhibited rapid infiltration capability, reducing the third liquid infiltration time by 13 s compared to those of commercial core layers while reducing reverse osmosis by 1.4 g, and the liquid absorption and retention rates are 47.7 times and 46.1 times, respectively, which is 1.6 times higher than those of commercial diapers. In addition, incorporating a natural antibacterial agent, ε-poly-l-lysine hydrochloride (ε-PLH), into the core layer resulted in an antibacterial rate exceeding 99.99% without direct contact with the skin; water transport capacity tests confirmed faster liquid infiltration speed, uniform absorption, and no fault formation.