Highly stretchable and super tough nanocomposite physical hydrogels facilitated by the coupling of intermolecular hydrogen bonds and analogous chemical crosslinking of nanoparticles

Abstract

Nanocomposite physical hydrogels fabricated by a one-step polymerization show ultra-extensibility and toughness due to an effective strengthening mechanism.

Transparent h- BN/polyacrylamide nanocomposite hydrogels with enhanced mechanical properties

“…Moreover, the h-BN/PAM nanocomposite hydrogels also significantly excel the PAM , and further to 600 kPa (0.12 wt%). These results are consistent with our previous reports [4][5][6][7][8][9]15] that the nanomaterials with quantities of functional groups can work as analogous crosslinking points to sustain the increased stress and maintain the configuration of the gel network. Compared with the hydrogels composited with GO and nanoclay, the relatively limited improvement in mechanical properties of the gel by h-BN in this paper is mainly because the maximum content of the h-BN (0.12 wt%) is much lower than that of GO or nanoclay in GO/PAM hydrogels [21,30] or nanoclay/PAM hydrogels [31,32].…”

“…However, most of the existing natural and synthetic hydrogels have poor mechanical properties, which unfortunately limit their applications in many fields where tough and flexible hydrogels are necessary. In this sense, a surge of research has been reported on the development of nanocomposite hydrogels reinforced with various nanofillers, including clay nanosheets [16], silica nanoparticles [6,9,17], graphene oxide (GO) nanosheets [7,[18][19][20][21][22] and carbon nanotubes [23]. Recently, we have prepared a high-strength GO/PAA nanocomposite hydrogels composed of a single network with dual crosslinking points through dynamic ionic interactions [7].…”

“…Recently, we have prepared a high-strength GO/PAA nanocomposite hydrogels composed of a single network with dual crosslinking points through dynamic ionic interactions [7]. GO nanosheets are not only nanofiller with extraordinary mechanical strength and large surface area, but also serve as analogous crosslinking points [4][5][6][7][8][9]15] in the gel network, which cooperate with reversible ionic cross-linking points among the polymer chains to endow the gel with super toughness and stretchability.…”

“…Basically, cross-linkings may be divided into two different types, i.e., chemical (covalent bonds) and physical (ionic bonds, hydrogen bonds, etc.). In the past decades, hydrogels have received increasing attention owing to a wide range of potential applications, including tissue engineering, drug delivery, membrane separation, electrolytes and soft robot [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, most of the existing natural and synthetic hydrogels have poor mechanical properties, which unfortunately limit their applications in many fields where tough and flexible hydrogels are necessary.…”

Synthetic self-assembled homogeneous network hydrogels with high mechanical and recoverable properties for tissue replacement

“…[22][23][24] The HN structure results in a smooth network stress distribution, contributing to the high deformability without fracture. 23,25,26 Moreover, Kamata et al reported that the HN hydrogels without hysteresis under their loading-unloading environment. 22 However, to the best of our knowledge, there has been a few report on the synthesis of HN hydrogels without crosslinking agent by a self-assembled polymerization process.…”