Fabrication and properties of high performance polyimide nanofibrous films by electrospinning

Polyimides (PIs) are a class of representative high-performance engineering plastics possessing the cyclic imide and aromatic groups. Aromatic polyimides have been extensively investigated due to their excellent thermal stability, mechanical properties, along with their good chemical resistance and dielectric properties. Carbon nanotubes (CNTs) have been widely used in many fields such as electrodes, nanometer electron device, and composites etc, as CNTs are considered as the ideal reinforcing nanofillers owing to low density, high aspect ratio, high stiffness, and extremely high strength. With the development of the electrospinning technology, PI nanocomposites containing CNTs have received more significant attention. However, only a few studies have described the conductive mechanism and mechanical properties of PI/CNTs nanocomposites by electrospinning. In this paper, in order to improve the interfacial interaction and compatibility between the MWNTs and the matrix, pristine MWNTs were firstly treated with concentrated HNO₃ to obtain the acid-functionalized MWNTs, and then the electrospinning solutions are prepared via in-situ polymerization. At last, PI nanofibers and the nanofiber composites with MWNTs were fabricated by electrospinning. The controllable structure such as parallel fiber is formed. The dispersion and alignment morphologies of MWNTs in the electrospun nanofibers, as well as the thermal and mechanical properties of the nanofiber composites, were studied in detail. The relationship between structure and electrical properties of the nanofiber composites are also studied. To sum up, such a homogeneity approach to fabricate high-performance PI/CNTs nanofiber films is a good attempt toward utilizing CNTs in polymer matrices to achieve excellent thermal, electrical, and mechanical properties in practical use.