Strengthening mechanism of poly(acrylamide)/graphene oxide/laponite dual nanocomposite hydrogels

Abstract

Laponite or graphene oxide (GO) is usually used as a multifunctional crosslinker or a nanofiller to improve the nanocomposite gel strength. To explore the strengthening mechanism of GO/Laponite-based dual nanocomposite hydrogels, we synthesized a dual nanocomposite hydrogel through in situ polymerization of acrylamide (AM) in the dispersion of GO and Laponite. The interactions between GO and Laponite were confirmed by rheological test. GO and Laponite nanosheets were exfoliated well and dispersed uniformly in the hydrogels at low concentration of GO. Crosslinking network and thermal behaviors were investigated with respect to the concentration of GO and Laponite. The gel exhibited a high mechanical strength of 391 kPa with extensibility of 1420% and a high toughness of 2.58 MJ/m 3 , which was expected to be applied in biological engineering field. GO is not a much more effective agent than Laponite due to formation of GO aggregates in high concentration of GO. This work provides a guidance for the synthesis of tough dual nanocomposite hydrogels.

Tough hybrid hydrogels based on simultaneous dual in situ sol–gel technique and radical polymerization

“…In the FTIR spectrum of dried PAM/SiO 2 /TiO 2 hybrid hydrogel [Figure (a)], the bands at 2925, 1655, and 1617 cm −1 could be ascribed to the characteristics of CH 2  stretching, CO stretching, and NH bending of PAM, respectively . Meanwhile, the band at around 1090 cm −1 has been identified as the SiOSi asymmetric stretching vibration, and the peaks at 883 and 553 cm −1 have been identified as the TiOTi vibration.…”

“…Recently, Xu and coworkers developed a dual nanocomposite hydrogel by introducing clay nanosheets (such as Laponite or bentonite) and the other inorganic component (such as graphene oxide, SiO 2 , or TiO 2 ) as hybrid crosslinker, and the mechanical properties of hydrogels were improved . The introduction of graphene oxide, SiO 2 , or TiO 2 nanoparticles which were obtained by MPTMS, TEOS, VTES, and tetrabutyl titanate (TBOT) as silica source or titanium source in universal sol–gel method. Then, a series of tough dual nanocomposite hydrogels with hybrid crosslinking networks by simultaneous sol–gel technique and free‐radical polymerization.…”

“…Thus, the key step to achieve tough nanocomposite hydrogels is to solve the compatibility problem between inorganic nanomaterials and polymer matrix. The in situ sol–gel process was regarded as an effective method to improve the compatibility of nanoparticles with polymer matrix and strength of nanocomposite hydrogels . It is well known that the sol–gel reaction involves the hydrolysis of nanoparticles precursors and the condensation of the resulting hydroxyl groups to form a network structure, which can prevent the nanoparticles from aggregation and improve the dispersion.…”

Effect of polyaspartic acid‐functionalized graphene oxide on the mechanical performance of polyimide‐based composites

“…7 Zhang et al achieved 139% increase in tensile strength and 33% increase in Young's modulus for 1.0 wt % graphene-reinforced fluorographene-reinforced PI composite films. [11][12][13][14][15] Furthermore, many macromolecular chains, such as polybenzimidazole, 16 polyaniline, 17 poly(vinylidene fluoride) (PVDF), 18 polyethylenimine, 19 and polyurethane 20 can anchor on these functional groups. 9 Graphene is a robust two-dimensional (2D) layer structure consisting of a hexagonal single-atom-thick nanosheet network of sp 2 -hybridized carbon atoms.…”

“…As one derivative of graphene, GO nanosheets possess many oxygen-containing functional groups on its surface and edges, which can help to improve the dispersibility of graphene considerably. [11][12][13][14][15] Furthermore, many macromolecular chains, such as polybenzimidazole, 16 polyaniline, 17 poly(vinylidene fluoride) (PVDF), 18 polyethylenimine, 19 and polyurethane 20 can anchor on these functional groups. Percec et al obtained polypyrrole/GO hybrid composites by using ammonium persulfate as an oxidant.…”