Superlight, Mechanically Flexible, Thermally Superinsulating, and Antifrosting Anisotropic Nanocomposite Foam Based on Hierarchical Graphene Oxide Assembly

Abstract

Lightweight, high-performance, thermally insulating, and antifrosting porous materials are in increasing demand to improve energy efficiency in many fields, such as aerospace and wearable devices. However, traditional thermally insulating materials (porous ceramics, polymer-based sponges) could not simultaneously meet these demands. Here, we propose a hierarchical assembly strategy for producing nanocomposite foams with lightweight, mechanically flexible, superinsulating, and antifrosting properties. The nanocomposite foams consist of a highly anisotropic reduced graphene oxide/polyimide (abbreviated as rGO/PI) network and hollow graphene oxide microspheres. The hierarchical nanocomposite foams are ultralight (density of 9.2 mg·cm) and exhibit ultralow thermal conductivity of 9 mW·m·K, which is about a third that of traditional polymer-based insulating materials. Meanwhile, the nanocomposite foams show excellent icephobic performance. Our results show that hierarchical nanocomposite foams have promising applications in aerospace, wearable devices, refrigerators, and liquid nitrogen/oxygen transportation.

Lightweight, mechanically flexible and thermally superinsulating rGO/polyimide nanocomposite foam with an anisotropic microstructure

“…18 Furthermore, the highly ordered cellular walls of the thermally insulating nanocomposite can effectively impede the heat transport in the radial direction and result in ultra-low in-plane thermal conductivity. 17,33 The exceptional attributes of GO nanosheets and PI polymeric building blocks, along with the intriguing anisotropic architectures, make the as-prepared rGO/PI nanocomposite foams as an attractive option for thermal management.…”

Graphene‐Based Ultralight Compartmentalized Isotropic Foams with an Extremely Low Thermal Conductivity of 5.75 mW m−1 K−1

“…As such, the observed range of thermal conductivities and the anisotropy ratios of their values according to the direction of thermal transport are summarized and compared in Figure 5E,F, respectively. [15,[18][19][20]49,50] In particular, the thermal insulation performances along the CCS direction are observed to be 1.15-11.2 times greater than those along the OCS direction. This contrasting anisotropy in the direction-dependent thermal insulation performance is mainly attributable to the higher Knudsen number for the CCS direction by which the gas conduction is effectively suppressed by numerous nanopores present at the walls along the CCS direction.…”

“…Subsequently, several studies have investigated advanced thermal insulating materials based on CCS foams aligned along a single direction. [16][17][18][19][20][21] However, these approaches have encountered several limitations in further improving the thermally insulating properties. First, the lack of capability of controlling the cell dimension and internal wall thickness results in an inevitable increase of solid conduction.…”

Fabrication of highly pressure-sensitive, hydrophobic, and flexible 3D carbon nanofiber networks by electrospinning for human physiological signal monitoring

“…6 Peng and co-workers proposed a hierarchical assembly strategy for fabricating nanocomposite foams with light weight, hydrophobicity, and superinsulating properties. 21 Despite these achievements, 3D materials have relatively low pressure-sensitivity and cannot simultaneously possess high sensitivity and versatile properties, which proposes a great challenge to fabricate multifunctional 3D materials with superior sensitivity.…”