Abstract
Flame-retardant and thermal management structures have attracted great attention due to the requirement of high-temperature exposure in industrial, aerospace, and thermal power fields, but the development of protective fire-retardant structures with complex shapes to fit arbitrary surfaces is still challenging. Herein, we reported a rotation-blade casting-assisted 3D printing process to fabricate nacre-inspired structures with exceptional mechanical and flame-retardant properties, and the related fundamental mechanisms are studied. 3-(Trimethoxysilyl)propyl methacrylate (TMSPMA) modified boron nitride nanoplatelets (BNs) were aligned by rotation-blade casting during the 3D printing process to build the “brick and mortar” architecture. The 3D printed structures are more lightweight, while having higher fracture toughness than the natural nacre, which is attributed to the crack deflection, aligned BN (a-BNs) bridging, and pull-outs reinforced structures by the covalent bonding between TMSPMA grafted a-BNs and polymer matrix. Thermal conductivity is enhanced by 25.5 times compared with pure polymer and 5.8 times of anisotropy due to the interconnection of a-BNs. 3D printed heat-exchange structures with vertically aligned BNs in complex shapes were demonstrated for efficient thermal control of high-power light-emitting diodes. 3D printed helmet and armor with a-BNs show exceptional mechanical and fire-retardant properties, demonstrating integrated mechanical and thermal protection.
Highlights
Lightweight and strong flame-retardant structures have been widely studied due to the need for high-performance thermal insulation in fire-fighting, military, industrial, and aerospace engineering [1, 2]
Several studies have been performed on the nacre-inspired structures and structures with aligned boron nitride nanoplatelets (BNs) (a-BNs) for anisotropic thermal conductivity and flame-retardant properties [3, 12, 13], but these structures are limited to thin films or simple bulk shapes with respective mechanical or thermal properties
We further demonstrate that a 3D printed heat sink with a branching structure shows efficient thermal control and heat dissipation for high-power light-emitting diodes (LEDs)
Summary
Lightweight and strong flame-retardant structures have been widely studied due to the need for high-performance thermal insulation in fire-fighting, military, industrial, and aerospace engineering [1, 2]. Research control/flame-retardant structures due to their good processibility and excellent mechanical, thermal, and electrical properties. The BM structure sheds light on tough ceramic/polymer composite structure design for thermal control and flame-retardant applications. Hexagonal boron nitride nanoplatelets (BNs) possess a flaky structure with exceptional mechanical, thermal, and flame stability, which make it an attractive option for applications in body armor, heat sinks, microcircuit packaging, and fire-retardant structures [8]. Accurate control of nacre-inspired alignment in 3D printing using highly viscous composites to fabricate high-performance multifunctional structures with arbitrary shapes is challenging. We report a rotation-blade casting-assisted 3D (rbc-3D) printing process to construct the nacre-inspired structure with reinforced mechanical properties, highly anisotropic thermal conductivity, and excellent flame-retardancy. The 3D printed nacre-inspired structure has a high loading of a-BNs (55 wt%) and possesses enhanced integrated mechanical/thermal/flame-retardant properties. 3D printed helmet and armor are demonstrated to have both flame-retardant and mechanical protective properties, which make them more desirable for future applications
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