Self-Healing Hydrogels Based on Carboxymethyl Chitosan and Acryloyl-6-aminocaproic Acid

Abstract

Once cracks have formed within hydrogel materials, the integrity of the structure is signifcantly compromised, regardless of the application. Here, we demonstrate cross-linked CMCS hydrogels can be engineered to exhibit self-healing under mild conditions. CMCS hydrogels based on CMCS and acryloyl-6-aminocaproic acid (A6ACA) were synthesized by free radical aqueous copolymerization using ammonium persulfate as initiator. A series of hydrogels was synthesized varying the percentage of A6ACA. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR) techniques and their morphologies were investigated by scanning electron microscope (SEM) images. When the proportion of A6ACA was increased, the compressive strength, stress, and strain of hydrogels were increased. The cross-linked hydrogel based on CMCS that can autonomously heal between cut surfaces after 1 h was formed under mild conditions. The increase of A6ACA content in the hydrogels will lead to increased mechanical properties and mechanical healing efficiencies for highly cross-linked polymeric networks. Hydrogen bond is the main reason for self-healing ability, and the covalent cross-linkss and noncovalent cross-links both bear loads in the hyrogel. Polymers with the ability to self-repair after sustaining damage could extend the lifetime of materials used in many applications.

Chitosan–Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm

“…Continuous robust hydrogel films were fabricated through the successful application of the self-healing ability of chitosan hydrogel network systems in contact with each other. This self-healing ability arises as a result of the strong hydrogen-bonding interactions among the hydrogel network macrosystems. − …”

“…Interestingly, the chitosan-based hydrogels were found to exhibit a self-healing property, namely, an ability by which two different hydrogel systems, when kept in contact with each other, can stick together and become one. Mainly, the strong electrostatic and hydrogen-bonding interaction abilities of chitosan are suspected to contribute to this self-healing phenomenom. − Here, we effectively utilized this self-healing ability of the chitosan hydrogel to prepare the desired films. The nanocomposite films were found to show a broad-spectrum antimicrobial activity with significant inhibitory effects when tested against both Gram-positive and Gram-negative bacterial strains, responsible for infections in wounds and the contamination of foodstuffs.…”

Synthesis of Silicon-Containing Chitosan Hydrogels in a Glycolic Acid Medium

“…However, unwanted condensation products, the unreacted crosslinker, and a decreased number of free binding sites (the amino groups of chitosan) affect the gel's biological properties adversely. Physical hydrogels are free of these disadvantages of chemically linked ones, since they are formed via various reversible interactions, ionic ones, in ioncrosslinked hydrogels [20,21], in polyelectrolyte complexes, or secondary interactions in grafted and interpenetrating hydrogels. For example, strong intermolecular hydrogen bonds are formed in the case of hybrid hydrogels of chitosan and gelatin [22], tripolyphosphate [23], glycerophosphate [24], agar [25,26], sebacic acid [27], polylactic-co-glycolic acid and polycaprolactone polyethers [28,29], silk fibroin [30], and hyaluronan [31].…”