An Innovative Approach for the Preparation of High-Performance Electrospun Poly(p-phenylene)-Based Polymer Nanofiber Belts

The aim of this study is to prepare high-performance poly(p-phenylene) (PPP)-based polymer nano fiber belts. The hypothesis is that these nanofiber belts would possess high mechanical properties, excellent thermal and chemical resistances, and unique electrical and photoelectrical characteristics owing to high rigidity of macromolecular backbones. In general, the unsubstituted PPP polymers are infusible and insoluble in common organic solvents; thus, the synthesis and processing of these polymers are intractable. Although some substituted PPP -based polymers (i.e., PPP derivations) are soluble, their molecular weights are too low to be processed into nanofibers (particularly by the electrospinning technique). To date, there has been no report on the preparation of any kind of PPP -based polymer nanofibers. In this study, four soluble PPP -based oligomers of phthalate-capped poly(2,5-benzophenone) (PBPA) with varied molecular weights were synthesized via Ni(II) complex-catalyzed cross-coupling reaction; subsequently, the blend nanofiber belts of poly(2,5-benzophenone) pyrrolone (PBPY) and polyimide (PI) were made by the combination of electrospinning and molecular coupling assembly techniques followed by heat treatment, wherein the use of poly(amic acid) (PAA, the precursor of PI) as carrier/glue polymer for assisting electrospinning is crucial for successful preparation of the nanofibers. The PBPY/PI nanofiber belts exhibited high mechanical strength, superior thermal stability, and chemical resistance; hence, they could be used as filtration media under high-temperature and/or corrosive conditions, and they could also be used as separators in batteries and supercapacitors. It is important to note that this is the first reported study on the preparation of PPP -based polymer nanofibers; additionally, this study also provides an innovative approach for making nanofibers from the polymers that cannot be electrospun directly.