Novel micro-nano PBO composite paper with unprecedented mechanical properties and heat resistance

PBO specialty paper is highly praised for its ultrahigh heat resistance but suffers greatly from poor mechanical properties. Herein, a unique selective exfoliation method was developed to prepare micro/nano-PBO composite paper composed of PBO chopped fibers (PBOCFs) and PBO nanofibers (PBONFs). The 3D interconnected PBONF network firmly adheres to the 1D PBOCF skeleton, which significantly enhances the interaction between fibers and reduces defects such as voids. As a result, the mechanical strength, modulus and electrical breakdown strength of the structurally optimized composite paper were as high as 351.4 MPa, 9.7 GPa and 101.7 kV/mm, respectively, which are dramatically improved compared with those of the original PBO paper (4.3 MPa, 1.4 GPa, and 30.5 kV/mm). Remarkably, the outstanding heat resistance of PBO paper (650 °C) is perfectly preserved. This new grade of specialty paper holds great potential as an electrical insulating material for extreme environments.