Research article

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Physically crosslinked chitosan hydrogels have better biocompatibility and possess unique functional characteristics but suffer from poor mechanical properties. In the current study, we prepared Cu⁺-containing physically crosslinked chitosan hydrogels by exploiting ammonia fumigation and reduction of Cu2⁺ by NaHSO3. The content of Cu⁺ in the prepared hydrogels was in a low range of 4.88–29.27 μmol/g. The mechanical strength of the CTS-Cu⁺/NH3 hydrogels was remarkably improved up to 0.25 MPa and the elongation at break increased with rising content of Cu⁺ due to the dynamic crosslinks between chitosan and Cu+. Moreover, the CTS-Cu⁺/NH3 hydrogels demonstrated evident shape memory after exposure to air by exploiting the different coordination number of Cu²⁺ and Cu⁺. Thus, the prepared hydrogels may have good potential applications as biomedical materials.