A Malleable Composite Dough with Well-Dispersed and High-Content Boron Nitride Nanosheets
Lanshu Xu, Ke Zhan, Siyuan Ding, Jiuyi Zhu, Minsu Liu, Weiren Fan, Pei Duan, Kai Luo, Baofu Ding, Bilu Liu, Yilun Liu, Hui–Ming Cheng, Ling Qiu
Abstract
Aggregation of two-dimensional (2D) nanosheet fillers in a polymer matrix is a prevalent problem when the filler loading is high, leading to degradation of physical and mechanical properties of the composite. To avoid aggregation, a low-weight fraction of the 2D material (<5 wt %) is usually used to fabricate the composite, limiting performance improvement. Here, we develop a mechanical interlocking strategy where well-dispersed high filling content (up to 20 wt %) of boron nitride nanosheets (BNNSs) can be incorporated into a polytetrafluoroethylene (PTFE) matrix, resulting in a malleable, easy-to-process and reusable BNNS/PTFE composite dough. Importantly, the well-dispersed BNNS fillers can be rearranged into a highly oriented direction due to the malleable nature of the dough. The resultant composite film has a high thermal conductivity (4408% increase), low dielectric constant/loss, and excellent mechanical properties (334%, 69%, 266%, and 302% increases for tensile modulus, strength, toughness, and elongation, respectively), making it suitable for thermal management applications in the high-frequency areas. The technique is useful for the large-scale production of other 2D material/polymer composites with a high filler content for different applications.