Highly Thermoconductive, Thermostable, and Super‐Flexible Film by Engineering 1D Rigid Rod‐Like Aramid Nanofiber/2D Boron Nitride Nanosheets

Abstract

Polymer‐based thermal management materials have many irreplaceable advantages not found in metals or ceramics, such as easy processing, low density, and excellent flexibility. However, their limited thermal conductivity and unsatisfactory resistance to elevated temperatures (<200 °C) still prevent effective heat dissipation during applications with high‐temperature conditions or powerful operation. Therefore, herein highly thermoconductive and thermostable polymer nanocomposite films prepared by engineering 1D aramid nanofiber (ANF) with worm‐like microscopic morphologies into rigid rod‐like structures with 2D boron nitride nanosheets (BNNS) are reported. With no coils or entanglements, the rigid polymer chain enables a well‐packed crystalline structure resulting in a 20‐fold (or greater) increase in axial thermal conductivity. Additionally, strong interfacial interactions between the weaved ANF rod and the stacked BNNS facilitate efficient heat flux through the 1D/2D configuration. Hence, unprecedented in‐plane thermal conductivities as high as 46.7 W m−1 K−1 can be achieved at only 30 wt% BNNS loading, a value of 137% greater than that of a worm‐like ANF/BNNS counterpart. Moreover, the thermally stable nanocomposite films with light weight (28.9 W m−1 K−1/103 (kg m−3)) and high strength (>100 MPa, 450 °C) enable effective thermal management for microelectrodes operating at temperatures beyond 200 °C.

A Biomimetic Transpiration Textile for Highly Efficient Personal Drying and Cooling

“…The characteristic peaks of BNNS at 1287 cm −1 assigned to B−N stretching and 750 cm −1 assigned to out‐of‐plane B−N−B bending, exhibited a decreased intensity and shift to 1355 and 765 cm −1 , respectively, with the PU additive. [ 36,40,41 ] Moreover, the randomly distributed BNNSs became highly aligned (bottom inset in Figure 2a) after drawing in the electric field during electrospinning. Note that the drawing‐induced thinning of the PU/BNNS fibers was affected by the phase separation of polymer solutions, which was mainly controlled by the modification of the tri‐solvent system and solid content in this work.…”

“…Specifically, strong interfacial interactions were formed between the elastic PU polymer and the highly aligned BNNS during electrospinning (top inset in Figure 2a), which facilitated the efficient heat flux through the fibrous membranes. [35,36] The crystal structure demonstrated that the PU polymer chain and the (B-N) 3 hexatomic rings were coupled together by hydrogen bonds NH•••N with distances of 2.57 and 2.85 Å. This interfacial interaction can be explained by the electrostatic potential (ESP) analysis, which is a favorable tool to gain information about the reactivity, charge distribution, and hydrogen bonding interaction (detailed in the Supporting Information).…”

Fully Organic Bulk Polymer with Metallic Thermal Conductivity and Tunable Thermal Pathways

“…Thermal management plays an increasingly important role in modern technologies, most notably electronics [ 1 , 2 , 3 ] and energy devices. [ 4 , 5 , 6 , 7 ] The ease of processing and electrical insulation properties of organic polymers has made them indispensable for these applications.…”

Ultra-Robust Thermoconductive Films Made from Aramid Nanofiber and Boron Nitride Nanosheet for Thermal Management Application

“…However, the primary reason for restricting its use in the field of heat dissipation is that polymers generally have a low thermal conductivity (0.2–0.5 W m −1 K −1 ) [ 3 , 4 ]. Therefore, a variety of thermally conductive fillers, such as graphene, hexagonal boron nitride (h-BN), aluminum nitride, aluminum oxide, and silicon carbide are usually used to improve the thermal conductivity of polymer composites and solve the problem of heat dissipation [ 5 , 6 , 7 , 8 , 9 , 10 ].…”