Strength enhanced expandable polyvinyl alcohol/chitosan cryogel for non-compressible hemostasis.

For penetrating and deep non-compressible bleeding, hemostatic materials need to meet the demand of easy filling and rapid expansion to close the wound. However, developing an expandable material with sufficient mechanical strength remains a challenge. This study proposed an improved non-solvent induced phase separation (NIPS) method to prepare polyvinyl alcohol/chitosan (PVA/CS) cryogel with large pore structure (70-75 um) and enhanced mechanical properties. The pore structure on the surface enables blood to quickly enter the dry and shape-fixed PVA/CS cryogel, triggering volume expansion. By regulating the hydrogen bond of PVA molecules by CS, the hydrophilia of cryogel was enhanced and the full volume recovery time of PVA/CS was shortened (27 ± 3 s). The aggregation of PVA molecular in solution enhances the crosslinking, endowing the prepared PVA/CS cryogel with good mechanical properties. The tensile strength of PVA/CS cryogel is up to 0.694 ± 0.044 MPa, and the compressive strength reach to 0.32 ± 0.04 MPa with 75 % compression. The good mechanical properties are beneficial for providing physical support. The preparation method does not require the introduction of toxic chemical cross-linking agents and complicated operation process, which has potential applications in non-compressible hemostasis.