Reversible shape memory polymers (SRMPs) have been identified as having great potential for biomedical applications due to their ability to switch between different shapes responding to stimuli. In this paper, a chitosan/glycerol (CS/GL) film with a reversible shape memory behavior was prepared, and the reversible shape memory effect (SME) and its mechanism were systematically investigated. The film with 40% glycerin/chitosan mass ratio demonstrated the best performance, with 95.7% shape recovery ratio to temporary shape one and 89.4% shape recovery ratio to temporary shape two. Moreover, it shows the capability to undergo four consecutive shape memory cycles. In addition, a new curvature measurement method was used to accurately calculate the shape recovery ratio. The suction and discharge of free water change the binding form of the hydrogen bonds inside the material, which makes a great reversible shape memory impact on the composite film. The incorporation of glycerol can enhance the precision and repeatability of the reversible shape memory effect and shortens the time used during this process. This paper gives a hypothetical premise to the preparation of two-way reversible shape memory polymers.

Zinc ions, as essential trace elements in the human body, play a crucial role in promoting wound healing. They have significant applications in the medical field. In this paper, chitosan (CS)/polyvinyl alcohol (PVA)/zinc gluconate hydrogel was synthesized via gamma ray irradiation cross-linking. The hydrogel exhibited excellent antibacterial properties, and could continuously release zinc ions. Antibacterial assays demonstrated that the combination of CS and zinc ions improved the antibacterial properties of hydrogel. The inhibition zones against both Staphylococcus aureus and Escherichia coli exceed 12 mm. The cell viability can reach 108.25%. The prepared hydrogel could continuously release zinc ions over a period of 70 h. The pore and chemical structure were, respectively, performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). And its comprehensive properties, such as gel content, water evaporation ratio and swelling behavior were investigated. The hydrogels showed potential application value in the hydrogel dressing for zinc ion delivery.