Abstract
Facile methods toward strain-tolerant graphene-based electronic components remain scarce. Although being frequently used to disperse low-dimensional carbonaceous materials, ultrasonication (US) has never been reliable for fabricating stretchable carbonaceous nanocomposite (SCNC). Inspired by the unusual sonochemical assembly between graphene oxide (GO) and carbon nanotube (CNT), we verified the roots-like GO–CNT covalent bonding, rather than just π–π conjugation, was formed during US. In addition, the shockwave-induced collision in the binary-component system enables a burst of fragmentation at the early stage, spatially homogeneous hybridization, and time-dependent restoration of graphitic domains. All of the above are distinct from extensive fragmentation of a conventional single-component system and π–π conjugative assembly. The optimized SCNC exhibits conductivity comparable to reduced monolayer GO and outperforms π–π assemblies in retaining electrical conductance at a strain of 160%—among one of the best reported stretchable conductors. Raman analysis and mechanics simulation confirm the dominant role of counterweighing between the intrinsic and external strains on the mechano-response and durability of SCNC. This work suggests the guideline of creating multiple-component sonochemical systems for various functional nanocomposites.
Highlights
US enables roots-like covalent bonding between graphene oxide (GO) and carbon nanotube (CNT), which was only realized before via chemical vapor deposition (CVD)
The estimated bandgap energy from light extinction is minimized at stretchable carbonaceous nanocomposite (SCNC)-15 (∼3.5 eV), while GO-15 and GO + CNT change little in comparison with p-GO (∼4.35 eV)
CNT is more likely to be rooted at the edge or a defective basal plane of GO at the initial stage of collision, as we found in SCNC-5 (Figure S14) and other work.[19]
Summary
The rapid development of the stretchable electronics inspired the pursuit of strain-tolerant conductive components that retain the integrity of structure and conductivity even under large strains.[1,2] Two-dimensional (2D) graphene has been reckoned as a highly promising candidate due to its intrinsic tensile strength (130 GPa), flexibility, low resistivity (10−6 Ω·cm) and negative Poisson’s ratio when the tensile strain exceeds 6%.3,4 Disappointingly, the overall conductivity of most reported graphene sheets is retained at less than 5% strain due to brittle fracture at unavoidable defect or strain-induced inhomogeneity of charge carriers mobility.[5−8] To enhance the strain tolerance, the monatomic graphene has been geometrically engineered into the mechano-responsive patterns, such as crumple[9,10] and kirigami.[11]. The vast majority of researchers believe the shockwave-induced π−π conjugation and lamellar spacing between graphitic domains dominates the superior stretchability and mechanical stability of nanocomposites to their parent materials.[15] few examples exist to argue this overtrusted claim in the context that the collisions among suspended solid particles arise during extreme heating at the point of impact to overcome the bonding energy barrier.[21,22] In a single-component system graphene oxide (GO)[23] or carbon nanotube (CNT)[24] dispersion as a typical model extensive sonication intensifies the fragmentation and structural damage, while in binary- or even multiplecomponent systems, the understandings of kinetics in bond cleavage, generation of active intermediates and high-velocity heterogeneous collision for bond formation/local fusion are quite vague.[25]. The mechano-responsive pattern outperforms π−π assemblies in retaining electrical conductance and structural integrity even at a strain of 160%
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