Full micro-nanofiber aerogel with three-dimensional fluffy network structure for rapid liquid absorption and uniform liquid retention in diapers

Diapers are essential for infants and patients with urinary incontinence. The super-absorbent polymer (SAP) in the core layer of diapers suffers from slow liquid absorption, fault formation, and reverse osmosis. Therefore, it is desirable to construct a core layer that can integrate rapid liquid absorption, uniform retention, and anti-seepage qualities. In this study, a diaper core layer and a three-dimensional fluffy network structure with a wetting gradient was constructed via one-step solution blow spinning (SBS). By regulating the content of the glutaraldehyde (GA) cross-linking agent, absorbent and insoluble fibers could be obtained. The ratio of super-absorbent fibers (SAF) to PAN-PVP micro-/nano fibers in the three-layer fiber structure and the gram weight of the core layer were adjusted. A wetting gradient was established when the weight of the adjusted gradient core layer was 2/3 that of the commercial core layer. The amount of reverse osmosis was reduced by 0.25 g, and the liquid absorption and retention were 30 times and 28.5 times, respectively, two and 3.5 times higher than those of commercial diapers. The SAF prepared by SBS could improve the core layer's liquid absorption rate, retention ratio, and comfort. The fibers are applicable in diapers, sanitary napkins, and other disposable products. [Display omitted] •Adopting air-jet spinning technology to build a three-dimensional fluffy network structure for the whole fiber aerogel, accelerating liquid infiltration, longitudinal diffusion significantly enhances the utilization area of the core layer.•By adjusting the ratio of PAN-PVP and SAF fibers, a water absorption gradient is constructed. When the weight of the third layer of water-absorption fiber accounts for 2/3 of the commercial core layer, the gradient core layer diaper can absorb 30 times of salt water and retain 28.5 times of water.•Adding the cross-linking agent GA and applying thermal cross-linking treatment to make fiber molecules and fibers form a three-dimensional cross-linking structure, preventing dissolution and loss of water absorption. The fibers still maintain resilience under a pressure of 500 g.