Self-healable, tough and highly stretchable ionic nanocomposite physical hydrogels

Abstract

We present a facile strategy to synthesize self-healable tough and highly stretchable hydrogels. Our design rationale for the creation of ionic cross-linked hydrogels is to graft an acrylic acid monomer on the surface of vinyl hybrid silica nanoparticles (VSNPs) for the growth of poly(acrylic) acid (PAA), and the obtained VSNP-PAA nanobrush can be used as a gelator. Physical cross-linking through hydrogen bonding and ferric ion-mediated ionic interactions between PAA polymer chains of the gelators yielded ionic nanocomposite physical hydrogels with excellent and balanced mechanical properties (tensile strength 860 kPa, elongation at break ∼2300%), and the ability to self-repair (tensile strength ∼560 kPa, elongation at break ∼1800%). The toughness and stretchability arise from the reversible cross-linking interactions between the polymer chains that help dissipate energy through stress (deformation) triggered dynamic processes. These unique properties will enable greater application of these hydrogel materials, especially in tissue engineering.

Self-healable, tough and highly stretchable hydrophobic association/ionic dual physically cross-linked hydrogels

“…Compared with the S-DPHF-0 gel, the cationic surfactant CTAB and PAA form a PAA/CTAB complex in the C-DPHF-0 gels, which leads to a more stable and strong hydrophobic association. 23,35 As ferric ions are introduced into the S-DPHF and C-DPHF gels, dual cross-linked structures form in virtue of the ionic complexation between the ferric ions and the carboxylic acid groups from the PAA chains. Moreover, ferric ions may connect the anionic surfactant SDBS and the carboxylic acid groups to form a more stable hydrophobic association, and further reinforce the S-DPHF gel.…”

Tough polypseudorotaxane supramolecular hydrogels with dual-responsive shape memory properties

“…Different from chemical cross-linkers, physical cross-linking consisting of multiple hydrogen bonds is a good candidate for energy dissipation. 39 To be specific, in this article, the physical polypseudorotaxane cross-linking based on hydrogen bonding is an effective means of dissipating the deformation energy applied to the system. When the hydrogel is compressed, the polypseudorotaxanes will slide with each other and a large amount of compressive energy is dissipated by hydrogen bonds between columnar polypseudorotaxanes, endowing the hydrogel with tough compressive mechanical properties.…”

“…In contrast to the heating process, in the cooling process, G 0 recovers its original value at a much lower temperature (32 1C) and a hysteresis loop is observed, which was also found in other thermal-sensitive polymer systems. 39,42 This hysteresis loop is a kinetically indicative phenomenon of the resistance to disintegration of entangled polymer chains forming the hydrogel network. Frequency sweep at different temperatures is carried out to further clarify the thermoplasticity of hydrogels.…”

Triggerable tough hydrogels for gastric resident dosage forms

“…A set of materials with the mechanical properties capable of potentially surviving the gastric environment are tough hydrogels. Though significant advancement has been made in fabricating hydrogels with tougher characteristics, including double-network 21–25 , topological 26–30 , and nanocomposite hydrogels 31–34 , these gels lack the capacity to be triggered to dissolve in physiological environments, an important property to ensure the maximal safety and removal of such a system that could reside in the gastric cavity for multiple days. Long-term gastric resident systems can be associated with gastric outlet obstruction and/or the development of an allergic reaction could ensue from a gastric drug depot.…”