Integrated Functional High‐Strength Hydrogels with Metal‐Coordination Complexes and H‐Bonding Dual Physically Cross‐linked Networks

Abstract

With the deepening of research on high-strength hydrogels, the multi-functional study of hydrogels has become a hot spot. In this paper, a dual cross-linked physical high-strength hydrogels is prepared by a relatively simple method. 2-Vinyl- 4,6-Diamino-2-vinyl-1,3,5-triazine (VDT) induces the formation of the first cross-linking points through the interaction of hydrogen bonds with poly(acrylamide-co-acrylic acid) (PAm-co-Ac) chains, then the secondary physical cross-linkers Fe that introduce ionic coordinates between Fe and -COO groups. Due to the synergistic effect of hydrogen bonding and ionic coordination, hydrogels possess high tensile strength (approx. 4.34 MPa), large elongation (approx. 17.64 times), and good healing properties under alkali solution after cutting into two pieces. Meanwhile, VDT contains diaminotriazine functional groups that easily form hydrogen bonds so that the polymer of hydrogels could absorb 5-fluorouridine. In addition, the contribution of ionic polymer segments enables pH to be sensitive to hydrogels and facilitates the adsorption of a large number of ionic monomers to form ionic conductive networks, the prepared hydrogel capacitor device has very high sensitivity to pressure and deformation, and can detect the movement behavior of the human body. The dual-physical cross-linked hydrogels had a selective adsorption to biological small molecules and could be assembled into a flexible wearable device with high sensitivity.

Recent Advances in Design Strategies for Tough and Stretchable Hydrogels

“…Li et al [66] . copolymerized a commercially available monomer, 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine (VDT), in the presence of AAm and AA, producing a P(AAm‐ co ‐AA‐ co ‐VDT) copolymer hydrogel.…”

“…(b) Illustration of the formation of P(AAm-co-AA-co-VDT) copolymer hydrogel via that DPC strategy. Reproduced from reference [66] with permission from Wiley-VCH.…”

“…Li et al [66] copolymerized a commercially available monomer, 2-vinyl-4,6-diamino-1,3,5-triazine (VDT), in the presence of AAm and AA, producing a P(AAm-co-AA-co-VDT) copolymer hydrogel. VDT, which contains the diaminotriazine functionality, helps in forming the first crosslinking points by strong hydrogen bonding interactions between the polymer chains.…”

High‐Performance Photochromic Hydrogels for Rewritable Information Record

“…Several methods for the construction of high‐strength hydrogels have been reported, including double‐network, [ 14,15 ] nanoreinforcement, [ 16 ] hybrid crosslink, [ 17,18 ] hydrophobic association, [ 19 ] and ion crosslink. [ 20,21 ] Among them, hybrid crosslink hydrogels exist simultaneous physical and chemical crosslink, [ 22 ] which reveals good tensile strength, elongation at break, and self‐healing performance. Besides, ion crosslink is more prominent for physically reinforcing hydrogels.…”

Mechanically Robust Elastomers Enabled by a Facile Interfacial Interactions‐Driven Sacrificial Network

“…Another group is supramolecular interaction as a sacrificial network, such as hydrogen bond network, [ 13–16 ] ionic bond network, [ 17,18 ] and metal‐ligand coordination bond. [ 19–21 ] Compared with covalent bond, such supramolecular interactions can rupture preferentially upon deformation to dissipate energy. To introduce the supramolecular interactions into the elastomer matrix, polymer chains often need some inevitable chemical modifications.…”