Broader contextCarbon foam is a three-dimensional (3D) porous carbon material with an interconnected network architecture. It is usually prepared by the carbonization/pyrolysis of foamed polymers. Recently, ultrathin and exible energy storage devices have attracted much attention to meet

Electrospun blend-polyimide (blend-PI) nanofibers with high tensile strength and toughness are highlighted in this article. The blend-PI nanofibers were prepared by electrospinning the binary blend of rigid and flexible polyamic acids, followed by thermal imidization. The method is simple and can be extended to other kinds of polyamic acids. The morphologies and structures of the blend-PI nanofibers were investigated by scanning electron microscopy (SEM) and wide-angle X-ray diffraction (XRD). The mechanical properties, thermal properties and miscibility of the blend-PI nanofibers were studied by a tensile test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The mechanical properties of the blend-PI nanofibers, including tensile strength, modulus, elongation at break and toughness, could be well-tuned by modifying the molar ratio of the rigid component (B-PI) and the flexible component (O-PI). The blend-PI nanofibers with B-PI/O-PI molar ratio of 4/6 had an ultra-high strength of 1.3 GPa with an excellent toughness of 82 J g À1 . All the blend-PI nanofibers showed thermal stability to above 500 C. The presence of only one glass transition temperature (T g ) suggested the good miscibility of the binary PIs in the blend-PI nanofibers. This study would provide completely new opportunities for modifying the properties of electrospun PI nanofibers.

Single electrospun co-PI nanofiber and aligned co-PI nanofiber belts containing pyrimidine units possessed superior mechanical strength and modulus.

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