# Engineering Ultraporous and Highly Stable Polyacrylonitrile/Poly(vinyl alcohol) Sponges with High Water Absorption Capacity

## TL;DR

Researchers created highly absorbent sponges from polyacrylonitrile and polyvinyl alcohol for use in water management and biomedical applications.

## Contribution

A novel four-stage process produces ultraporous sponges with exceptional water absorption and stability.

## Key findings

- The sponges achieved a water absorption capacity of up to 16000% of their dry weight.
- The wet sponges showed greater elongation and compliance compared to dry sponges.
- Microstructural changes during stretching were observed using in situ tensile testing and micro-CT analysis.

## Abstract

Ultraporous sponges capable of absorbing large quantities
of water-based
liquids are of great interest in various fields of research. In this
study, ultraporous polyacrylonitrile/poly­(vinyl alcohol) (PAN/PVA)
sponges with exceptional water absorption capacityup to 16000%
of their dry weightwere produced through a four-stage process:
electrospinning, short fiber suspension creation, freeze-drying, and
PVA cross-linking with different maleic anhydride (MA) concentrations.
Characterization by electron microscopy and X-ray microscopy revealed
a porosity of 90% and an average fiber thickness of 0.4 μm.
Mechanical tests demonstrate that the wet sponge is more compliant
and experiences greater elongation than the dry sponge, with failure
occurring below 20% strain in dry samples and above 40% when wet. In situ tensile testing in a micro-CT scanner and digital
volume correlation analysis reveal significant morphological changes
during stretching, including strain localization and microstructural
variations. These findings provide insights into the mechanical behavior
of the PAN/PVA sponges and identify regions that are prone to fracture.
By the combination of electrospun PAN and PVA fibers in a stabilized
ultraporous architecture, this work introduces a practical and efficient
strategy for producing lightweight hydrophilic sponges for applications
in water management, biomedical devices, and tissue engineering.