Highly Anisotropic Thermal Conductivity of Layer-by-Layer Assembled Nanofibrillated Cellulose/Graphene Nanosheets Hybrid Films for Thermal Management

Abstract

An anisotropic thermally conductive film with tailorable microstructures and macroproperties is fabricated using a layer-by-layer (LbL) assembly of graphene oxide (GO) and nanofibrillated cellulose (NFC) on a flexible NFC substrate driven by hydrogen bonding interactions, followed by chemical reduction process. The resulting NFC/reduced graphene oxide (RGO) hybrid film reveals an orderly hierarchical structure in which the RGO nanosheets exhibit a high degree of orientation along the in-plane direction. The assembly cycles dramatically increase the in-plane thermal conductivity (λ) of the hybrid film to 12.6 W·m·K, while the cross-plane thermal conductivity (λ) shows a lower value of 0.042 W·m·K in the hybrid film with 40 assembly cycles. The thermal conductivity anisotropy reaches up to λ/λ = 279, which is substantially larger than that of similar polymeric nanocomposites, indicating that the LbL assembly on a flexible NFC substrate is an efficient technique for the preparation of polymeric nanocomposites with improved heat conducting property. Moreover, the layered hybrid film composed of 1D NFC and 2D RGO exhibits synergetic mechnical properties with outstanding flexibility and a high tensile strength (107 MPa). The combination of anisotropic thermal conductivity and superior mechanical performance may facilitate the applications in thermal management.

Allotrope carbon materials in thermal interface materials and fuel cell applications: A review

“…A series of studies investigated paper‐based TIMs with cellulose in composite with functionalized graphene. Song et al integrated nanofibrillated cellulose and graphene nanosheets for thermal management . Jeon and coworkers also studied the interaction between graphene and cellulose by varying six types of commercially available paper for TIMs fabrication.…”

“…Song et al integrated nanofibrillated cellulose and graphene nanosheets for thermal management. [105][106][107] Jeon and coworkers also studied the interaction between graphene and cellulose by varying six types of commercially available paper for TIMs fabrication. They found that the thermal conductivity of the in-plane graphene-coated paper is 6.78 W (m K) −1 , and that of bare paper is 0.05 W (m K) −1 .…”

Electrospun hyperbranched polylactic acid–modified cellulose nanocrystals/polylactic acid for shape memory membranes with high mechanical properties

“…CNCs have significant mechanical strength, aeolotropism, and elasticity because of their highly well‐aligned layering. Over the past decade, it has attracted wide attention in the fields of tissue engineering and material engineering . Huang et al prepared silk fibroin nanofiber membrane enhanced with CNCs by electrospinning; the tensile strength of these membranes were almost two times that of non‐reinforced silk fibroin nanofiber membranes.…”

Enhancement of thermal conductivity in polyamide-6/graphene composites via a “bridge effect” of silicon carbide whiskers

“…The thermal conductivity is obtained by the formula: K ¼ a  r  C p , where a is the thermal diffusivity, r is the mass density and C p is the specic heat of the sample. The detailed mechanism and methodology of the laser ash system have ever been reported in our previous study 27,28 ( Fig. S2 †).…”