Highly Thermally Conductive Fluorinated Graphene/Aramid Nanofiber Films with Superior Mechanical Properties and Thermostability

An Engineered Heterostructured Trinity Enables Fire-Safe, Thermally Conductive Polymer Nanocomposite Films with Low Dielectric Loss

To adapt to the trend of increasing miniaturization and high integration of microelectronic equipments, there is a high demand for multifunctional thermally conductive (TC) polymeric films combining excellent flame retardancy and low dielectric constant (ε). To date, there have been few successes that achieve such a performance portfolio in polymer films due to their different and even mutually exclusive governing mechanisms. Herein, we propose a trinity strategy for creating a rationally engineered heterostructure nanoadditive (FG@CuP@ZTC) by in situ self-assembly immobilization of copper-phenyl phosphonate (CuP) and zinc-3, 5-diamino-1,2,4-triazole complex (ZTC) onto the fluorinated graphene (FG) surface. Benefiting from the synergistic effects of FG, CuP, and ZTC and the bionic lay-by-lay (LBL) strategy, the as-fabricated waterborne polyurethane (WPU) nanocomposite film with 30 wt% FG@CuP@ZTC exhibits a 55.6% improvement in limiting oxygen index (LOI), 66.0% and 40.5% reductions in peak heat release rate and total heat release, respectively, and 93.3% increase in tensile strength relative to pure WPU film due to the synergistic effects between FG, CuP, and ZTC. Moreover, the WPU nanocomposite film presents a high thermal conductivity (λ) of 12.7 W m-1 K-1 and a low ε of 2.92 at 106 Hz. This work provides a commercially viable rational design strategy to develop high-performance multifunctional polymer nanocomposite films, which hold great potential as advanced polymeric thermal dissipators for high-power-density microelectronics.

A novel strategy to prepare high performance multifunctional composite films by combining electrostatic assembly, crosslinking, topology enhancement and sintering

Currently, polymer-fiber composite films face the challenge of striking a balance between good mechanical properties and multi-functionalities. Here, aramid fibers (ANFs), chitosan (CS) dendritic particles, and silver nanowires (AgNWs) were used to create high-performance multifunctional composite films. AgNWs and polymer dendritic particles form an interpenetrating segregated network that ensures both a continuous conductive filler and a polymer network. Electrostatic assembly eliminates repulsion between negatively charged ANFs, cross-linked CS particles generate a stable three-dimensional network, and a "brick-mortar" structure composed of multiple materials contributes to topological enhancement. Sintering encourages local overlap and fusing of the AgNWs while reducing their internal flaws. Based on the above strategy, these films achieve a strength of 306.5 MPa, a toughness of 26.5 MJ m-3, and a conductivity of 392 S cm-1. Density functional theory (DFT) and Comsol simulations demonstrate that the introduction of CS thin layers leads to strong hydrogen bonds and three-dimensional continuous conductive networks. With its outstanding mechanical and electrical properties, the AgNW@ANF/CS-CH film demonstrates excellent electromagnetic shielding (22 879.1 dB cm2 g-1) and Joule heating (70 °C within 10 s) capabilities. This work presents a novel approach to fabricate high-performance conductive films and expand their potential applications in lightweight wearable electronics and electrothermal therapy.