Achieving Highly Anisotropic Three-Dimensional, Lightweight, and Versatile Conductive Wood-Graphene Composite

Functionality of wood has to evolve with time to adapt to the emerging needs in society. In this work, endowing electrical conductivity to the insulating wood by adding graphene into the wood matrix to form a conductive wood-graphene composite (conductive wood) via a facile and environmentally benign fabrication technique. The rationale of fabricating conductive wood is of two folds: (1) The high suitability of wood as a renewable matrix due to its porous network and mechanically robust monolithic structure. (2) The need to explore reasonable strategy to adequately translate the properties of graphene from microscopic level to macroscopic level. The conductive wood is able to preserve both the natural features of wood (to function as mechanical scaffold) and the conductivity of graphene. An outstanding electrical conductivity (volume resistivity of 36.7 Ω·cm) is achieved for the conductive wood, while it can maintain a low bulk density of 0.44 g cm-1. More significantly, the conductive wood demonstrates a highly three-dimensional anisotropic conductivity that makes it a highly versatile conductor in various applications. Hence, this lightweight conductive wood may contribute towards a great electronic revolution and as an encouraging strategy to repurpose the function of wood in this new era.

Problem of Determining the Anisotropic Conductivity in Electrodynamic Equations

For a system of electrodynamic equations, the inverse problem of determining an anisotropic conductivity is considered. It is supposed that the conductivity is described by a diagonal matrix σ(x) = $${\text{diag}}({{\sigma }_{1}}(x),{{\sigma }_{2}}(x)$$, σ3(x)) with $$\sigma (x) = 0$$ outside of the domain Ω = $$\{ x \in {{\mathbb{R}}^{3}}|\left| x \right| < R\} $$, $$R > 0$$, and the permittivity ε and the permeability μ of the medium are positive constants everywhere in $${{\mathbb{R}}^{3}}$$. Plane waves coming from infinity and impinging on an inhomogeneity localized in Ω are considered. For the determination of the unknown functions $${{\sigma }_{1}}(x)$$, $${{\sigma }_{2}}(x)$$, and $${{\sigma }_{3}}(x)$$, information related to the vector of electric intensity is given on the boundary S of the domain Ω. It is shown that this information reduces the inverse problem to three identical problems of X-ray tomography.

Self-assembled Cellulose Nanofiber-Carbon Nanotube Nanocomposite Films with Anisotropic Conductivity

In this study, a nanocellulose-based material showing anisotopic conductivity is introduced. The material has up to 1000 times higher conductivity along dry-line boundary direction than along radial direction. In addition...