Graphene Aerogel/Epoxy Composites with Exceptional Anisotropic Structure and Properties

Abstract

3D interconnected graphene aerogels (GAs) are prepared through one-step chemical reduction and rational assembly of graphene oxide (GO) sheets, so that the difficulties to uniformly disperse the individual graphene sheets in the polymer matrixes are avoided. Apart from ultralow density, high porosity, high electrical conductivity, and excellent compressibility, the resulting GAs possess a cellular architecture with a high degree of alignment when the graphene content is above a threshold, ∼0.5 wt %. The composites prepared by infiltrating GA with epoxy resin present excellent electrical conductivities, together with high mechanical properties and fracture toughness. The unusual anisotropic structure gives rise to ∼67% and ∼113% higher electrical conductivity and fracture toughness of the composites, respectively, in the alignment direction than that transverse to it.

Mechanically robust honeycomb graphene aerogel multifunctional polymer composites

“…6e). Overall, GAPC shows better electro-mechanical stability and electrical sensitivity than other reported graphene-based composites under external deformation conditions [13,16,[24][25][26][27][28][29][30][31].…”

“…Consequently, inferior electrical conductivities (1 · 10 À7 to 1 · 10 À1 S/cm) have been reported in previous work for graphene-based composites [12,[20][21][22][23][24][25][26][27]. Furthermore, poor dispersion of graphene sheets in matrices may cause fractures and weak interfaces within the composites that compromise mechanical and thermal properties [28][29][30][31][32][33][34].…”

“…As shown in Fig. 6a, the electrical conductivity of GAPC depends on the GA loading fraction and at 1 wt% (0.44 vol%) loading is 1 S/cm, which is 2-7 times higher than that of conventional graphene-based composites [17,[24][25][26][27][28][29]31,36,38,43] (see Table S2). The high electrical conductivity of GAPC is attributed to the wellinterconnected GA frameworks.…”

“…Strong agents (e.g., HI and NaI) or inappropriate processing temperatures could cause severe shrinkage of GOA and a high density of structural defects on graphene sheets (I D /I G = 1.44 for HI and 1.54 for NaI) (Figs. S8 and S9) [27,[37][38][39]42,43,51,54]. The optimized dialysis process (20 vol% ethanol for 24 h) protects samples from frost heaving during the freezing process at À80°C (Fig.…”

“…Although 3D graphene monoliths and their composites have shown outstanding properties and promising potential for practical applications [17,[24][25][26][27][28][29]31,[36][37][38][39]42,43,[47][48][49][50][51][52][53][54], many properties (e.g., Young's Modulus, thermal and electrical conductivity) remain far below those of the individual graphene sheets [45]; this circumstance is mainly attributable to the irregular frameworks of GA materials or inadequate cross-linked connections between graphene sheets [27,36-39 ,42,43,47-54] (a summary of the state-of-the-art reports is included in Supplementary material, Tables S1 and S2). Moreover, most graphene oxide precursors used for fabrication of 3D graphene monoliths have small lateral dimensions (approx.…”