Lightweight conductive porous graphene/thermoplastic polyurethane (TPU) foams with ultrahigh compressibility were successfully fabricated by using the thermal induced phase separation (TISP) technique. The density and porosity of the foams were calculated to be about 0.11 g cm−3 and 90% owing to the porous structure. Compared with pure TPU foams, the addition of graphene could effectively increase the thickness of the cell wall and hinder the formation of small holes, leading to a robust porous structure with excellent compression property. Meanwhile, the cell walls with small holes and a dendritic structure were observed due to the flexibility of graphene, endowing the foam with special positive piezoresistive behaviors and peculiar response patterns with a deflection point during the cyclic compression. This could effectively enhance the identifiability of external compression strain when used as piezoresistive sensors. In addition, larger compression sensitivity was achieved at a higher compression rate. Due to high porosity and good elasticity of TPU, the conductive foams demonstrated good compressibility and stable piezoresistive sensing signals at a strain of up to 90%. During the cyclic piezoresistive sensing test under different compression strains, the conductive foam exhibited good recoverability and reproducibility after the stabilization of cyclic loading. All these suggest that the fabricated conductive foam possesses great potential to be used as lightweight, flexible, highly sensitive, and stable piezoresistive sensors.

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Lightweight conductive graphene/thermoplastic polyurethane foams with ultrahigh compressibility for piezoresistive sensing

Ultralight, high-performance electromagnetic interference (EMI) shielding graphene foam (GF)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites are developed by drop coating of PEDOT:PSS on cellular-structured, freestanding GFs. To enhance the wettability and the interfacial bonds with PEDOT:PSS, GFs are functionalized with 4-dodecylbenzenesulfonic acid. The GF/PEDOT:PSS composites possess an ultralow density of 18.2 × 10–3 g/cm3 and a high porosity of 98.8%, as well as an enhanced electrical conductivity by almost 4 folds from 11.8 to 43.2 S/cm after the incorporation of the conductive PEDOT:PSS. Benefiting from the excellent electrical conductivity, ultralight porous structure, and effective charge delocalization, the composites deliver remarkable EMI shielding performance with a shielding effectiveness (SE) of 91.9 dB and a specific SE (SSE) of 3124 dB·cm3/g, both of which are the highest among those reported in the literature for carbon-based polymer composites. The excelle...

Ultralight Graphene Foam/Conductive Polymer Composites for Exceptional Electromagnetic Interference Shielding

Construction, mechanism and prospective of conductive polymer composites with multiple interfaces for electromagnetic interference shielding: A review

The combination of carbon materials and ferrite materials has recently attracted increased interest in microwave absorption applications. Herein, a novel composite with cobalt cores encapsulated in a porous carbon shell was synthesized via a facile sintering process with a cobaltic metal–organic framework (Co-MOF-74) as the precursor. Because of the magnetic loss caused by the Co cores and dielectric loss caused by the carbon shell with a unique porous structure, together with the interfacial polarization between two components, the ferromagnetic composite exhibited enhanced electromagnetic wave absorption performance compared to traditional ferrite materials. With the thermal decomposition temperature of 800 °C, the optimal reflection loss value achieved −62.12 dB at 11.85 GHz with thin thickness (2.4 mm), and the bandwidth ranged from 4.1 to 18 GHz with more than 90% of the microwave that could be absorbed. The achieved performance illustrates that the as-prepared porous Co–C core–shell composite shows ...

Porous Co-C Core-Shell Nanocomposites Derived from Co-MOF-74 with Enhanced Electromagnetic Wave Absorption Performance.

Carbon materials and their composites for electromagnetic interference shielding effectiveness in X-band

3D network porous polymeric composites with outstanding electromagnetic interference shielding

The effective thermal conductivity of polystyrene (PS)/epoxy (EP) composites filled with aluminum nitride (AlN) nanoparticles and multi-wall carbon nanotubes (MWCNTs) was investigated. The surface of aluminum nitride and MWCNTs were modified in order to fit the nonpolar property of polystyrene and the polar one for epoxy, respectively. A “double synergistic effect” of enhancement on effective thermal conductivity of the composite was observed, which was profited from the selective localization of hybrid fillers and the formation of three-dimensional thermal transfer pathways. The maximum effective thermal conductivity achieved was 6.09 W/m·K with double-phase matrix, which is about 29 times of the pure epoxy and 50 % higher than the composite with single epoxy matrix at the same filler loading. Moreover, it was found that the composite with “double synergistic effect” is more easily to form 3D heat conductive path under low filler loading, which could be promising for the improvement of processability and facilitating considerable reduction of the cost.

Le Guo

Papers

3D network porous polymeric composites with outstanding electromagnetic interference shielding

Thermally conductive polystyrene/epoxy nanocomposites fabricated by selective localization of hybrid fillers