Self-healable, super tough graphene oxide–poly(acrylic acid) nanocomposite hydrogels facilitated by dual cross-linking effects through dynamic ionic interactions

Abstract

Here we propose a facile, one-pot in situ free radical polymerization strategy to prepare self-healable, super tough graphene oxide (GO)/poly(acrylic acid) (PAA) nanocomposite hydrogels by using Fe 3+ ions as a cross-linker. The 3-dimensional network structure of the GO/PAA nanocomposite hydrogels is facilitated by dual cross-linking effects through dynamic ionic interactions: (i) first cross-linking points 10 are Fe 3+ ions creating ionic cross-linking among PAA chains; (ii) second cross-linking points are GO nanosheets linking PAA chains through Fe 3+ coordination. When the GO/PAA nanocomposite hydrogels are under stretching, the ionic interactions among PAA chains can dynamically break and recombine to dissipate energy, while the GO nanosheets coordinated to the PAA chains maintain the configuration of the hydrogels and work as stress transfer centers transferring the stress to the polymer matrix. In this 15 regard, the GO/PAA nanocomposite hydrogels exhibit superior toughness (tensile strength = 777 kPa, work of extension = 11.9 MJ m -3 ) and stretchability (elongation at break = 2980%). Furthermore, after being treated at 45 o C for 48 h, the cut-off GO/PAA nanocomposite hydrogels exhibit a good self-healing property (tensile strength = 495 kPa, elongation at break = 2470%). The self-healable, super tough GO/PAA nanocomposite hydrogels lay a basis for developing advanced soft materials holding potential 20 applications in modern biomedical engineering and technology.

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

“…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.…”

“…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].…”

“…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]. 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.…”

“…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.…”

Facile one-pot synthesis and self-healing properties of tetrazole-based metallopolymers in the presence of iron salts

“…Nowadays, selfhealing materials [6][7][8][9][10][11][12] are under rapid development to improve the lifetime, safety, energy efficiency and environmental impact of synthetic materials. The past few decades have witnessed a rapid development in exerting such features into articial systems where polymers are used for self-healing applications.…”