Fiber breakage is found to be a ubiquitous phenomenon during the thermal treatments for electrospun nanofibers, because of the presence of solvent molecules and unrelaxed assembly of polymer chains. Here a strengthening strategy is designed by introducing a pre-heating stage for the as-spun nanofibers. At a temperature above the polymer’s glass transition temperature, the chains can get sufficiently relaxed by the aid of hot solvent, and at the same time, the solvent confined in the entangled chains can fully and steadily evaporate, but not erupt, off the nanofiber, when the temperature is just as high as the boiling point. Therefore, the nanofibers become more uniform in structure and can withstand the subsequent thermal reactions. For polyacrylonitrile-based electrospinning, such strategy can improve the final tensile strength from 42 to 112 MPa for the nanofiber films.

发现纤维断裂是在电纺纳米纤维热处理过程中普遍存在的现象，这是由于存在溶剂分子和聚合物链的无松弛组装。在这里，通过为初纺纳米纤维引入预热阶段来设计强化策略。在高于聚合物玻璃化转变温度的温度下，借助热溶剂可使链充分松弛，同时，缠结在链中的溶剂可以完全稳定地从纳米纤维中蒸发，但不会喷出，当温度刚好达到沸点时 因此，纳米纤维在结构上变得更加均匀并且可以承受随后的热反应。对于聚丙烯腈基静电纺丝，