Self-healing hydrogels containing reversible oxime crosslinks

Abstract

Self-healing oxime-functional hydrogels have been developed that undergo a reversible gel-to-sol transition via oxime exchange under acidic conditions. Keto-functional copolymers were prepared by conventional radical polymerization of N,N-dimethylacrylamide (DMA) and diacetone acrylamide (DAA). The resulting water soluble copolymers (P(DMA-stat-DAA)) were chemically crosslinked with difunctional alkoxyamines to obtain hydrogels via oxime formation. Gel-to-sol transitions were induced by the addition of excess monofunctional alkoxyamines to promote competitive oxime exchange under acidic conditions at 25 °C. The hydrogel could autonomously heal after it was damaged due to the dynamic nature of the oxime crosslinks. In addition to their chemo-responsive behavior, the P(DMA-stat-DAA) copolymers exhibit cloud points which vary with the DAA content in the copolymers. This thermo-responsive behavior of the P(DMA-stat-DAA) was utilized to form physical hydrogels above their cloud point. Therefore, these materials can either form dynamic-covalent or physically-crosslinked gels, both of which demonstrate reversible gelation behavior.

Self‐Healing Polysaccharide Hydrogel Based on Dynamic Covalent Enamine Bonds

“…Self‐healing hydrogels offer substantial benefits to extend the life span of hydrogel material due to its excellent intrinsic healing ability to repair themselves after destruction. Nowadays, the preparation of self‐healing hydrogels is mainly based on dynamic chemistry, including dynamic covalent chemistry and non‐covalent chemistry .…”

Recovery property of double-network hydrogel containing a mussel-inspired adhesive moiety and nano-silicate

“…S2), which further indicated irreversible breakage of covalent bonds within the polymer network. 45, 46 On the other hand, there was no significant difference between the measured G’ and G” values between the virgin D10L2/DN and those that were compressed to a strain of 0.5. This result further confirmed that the presence of DMA and Laponite minimized changes to the mechanical properties and the architecture of the DN hydrogel.…”

Fusion of Different Crosslinked Polymers Based on Dynamic Disulfide Exchange

“…Over the last decades, many DCBs have been reported based on for example, imine exchange, transesterification, olefin metathesis, reversible boronic ester formation, and dichalcogenide bond exchange . In addition, various studies on CLPs, including DCBs, have revealed that CLPs that contain DCBs show a variety of functionalities, such as self‐healing, shape memory, reversible sol‐gel reactions, stress relaxation, and reprocessing . Especially self‐healing based on bond‐exchange reactions is expected to prolong the lifetime of materials by preventing fatal structural disintegration.…”