Coordinating chain crystallinity and orientation by tailoring electrical stretching for fabrication of super-tough and strong organic fibers

High-performance fibers generally require both plastic deformation resistance (strength) and high damage tolerance (toughness). Nevertheless, strength and toughness are inherently incompatible because of the unsatisfied supramolecular structure of polymer fibers. Herein, the principle of coordinating chain crystallinity and orientation by electrospinning technique is shown to resolve the conflict between super toughness and high strength. Using polyethylene terephthalate (PET) as the model system, chain crystallinity and alignment can be simultaneously and dynamically manipulated with polymer ultrafine fibers (UFFs) by precisely controlling the electrical stretching of a spinning jet. The obtained PET UFFs, characterized by loosely packed but highly aligned chain stacks, possessed a true strength of 853 MPa (similar to that of spider dragline silk), super toughness of 415 MJ/m3 (2.5 times higher than that of spider dragline silk), and extraordinary true strain of 210% (four times higher than that of spider dragline silk and exceeding that of highly elastic Spandex filaments). This facile strategy may offer a new paradigm for the development of advanced super-tough and robust materials.