Enhancing mechanical strength of hydrogels via IPN structure

Abstract

In this investigation, polyacrylamide (PAAm) as the flexible network is introduced to enhance the mechanical strength of hyaluronic acid-gelatin (HA-Gel) hydrogels by interpenetrating polymer network (IPN). The structure, mechanical property, and rheology property of the IPN hydrogels are investigated. It is found that the compressive strength of the HA-Gel/PAAm IPN hydrogels has increased five times higher than that of HA-Gel hydrogels. Rheological test demonstrates that elastic moduli (G 0 ) and viscous moduli (G 00 ) of HA-Gel/PAAm IPN hydrogels increase 100 times higher than those of HA-Gel hydrogels. Moreover, the HA-Gel hydrogels are fractured under the low compressive stress, whereas HA-Gel/PAAm IPN hydrogels are not broken under the high compressive stress. It is envisioned that the IPN hydrogels will be an effective approach to enhance the mechanical strength and broaden the range of hydrogels' applications.

Tunable Interpenetrating Polymer Network Hydrogels Based on Dynamic Covalent Bonds and Metal–Ligand Bonds

“…A dual network is generally made of the same polymer cross-linked by two different types of bonds, often a covalent and a supramolecular bond, or two types of supramolecular bonds, ,− while IPNs comprise two or more interlaced polymer networks that are not covalently bonded to each other. The latter systems have gained broad interest because they allow a combination of the desired properties of each network (e.g., stimuli responsiveness), and even more, because they may exhibit new properties that are not observed in the component networks alone. − Most notably, IPN hydrogels may show enhanced mechanical properties such as greater toughness, larger extensibility, and improved strength due to synergistic interactions between the component networks that transfer the stress and dissipate mechanical energy upon deformation. ,, Recently, the combination of DCB and supramolecular interactions has been also reported to fabricate responsive IPN hydrogels and elastomers with outstanding mechanical performances. − For example, Konkolewicz et al synthesized a double dynamic IPN elastomer with superior mechanical (increased stress and strain at break, increased malleability, greater toughness) and self-healing properties based on Diels–Alder adduct and hydrogen bonding. Liang et al prepared highly stretchable IPN hydrogels with the properties of actuation, shape memory, and self-healing capability using boronic ester bonds and alginate–Ca 2+ complexation.…”

Robust hydrogel of regenerated cellulose by chemical crosslinking coupled with polyacrylamide network

“…On the other hand, friction among polymer chains can be enhanced largely and restrict the movement of the chains by introducing PAAm network into RC hydrogels. So compared to SN hydrogels, it need more force to achieve the same strain when the RC/PAAm DN hydrogels are compressed …”

Shear Responsive Gelation of Aqueous Polyacrylic Acid-co-polyacrylamide: Molecular Mechanism and Tribological Applications

“…Furthermore, they are nonrenewable, thus resulting in limited service lifetimes. 18,19 Therefore, obtaining hydrogel materials that can regenerate under mechanical action is crucial to overcome the currently insufficient lifetimes of hydrogel-based lubricants.…”

“…However, the mechanical strength of hydrogels is generally weak, and they are prone to structural damage under continuous shear during friction. Furthermore, they are nonrenewable, thus resulting in limited service lifetimes. , Therefore, obtaining hydrogel materials that can regenerate under mechanical action is crucial to overcome the currently insufficient lifetimes of hydrogel-based lubricants.…”