![]() Nature can always provide inspirations for us to remedy this troublesome conflict between strength and toughness. Besides pursuing high tensile strength, further improving their elongation and toughness is still a significant challenge. Therefore, this dilemma is quite common for previously reported nanocellulose-based macrofibers. Generally, compared with strength and stiffness, elongation and toughness are even more critical for fiber materials, especially for those relative to textile applications. For example, mechanical stretching can improve the NFC/CNC orientation resulting in marked improvement of tensile strength and stiffness, but meanwhile leads to obvious embrittlement and low failure strain. However, as strength and toughness are always mutually exclusive for manmadex structural materials, almost all the achievements ultimately came at the expense of elongation and toughness of the obtained macrofibers. As a result, significant enhancements in strength and stiffness have been achieved in the resultant nanocellulose-based macrofibers. Various strategies, such as flow-assisted assembly, combining wet-spinning with mechanical stretching or chemical crosslinking, mixing synergetic constituents together, have been pursued to strengthen the nanofiber alignment or enhance the interfibrillar interactions, etc. These extremely fine natural polymeric nanofibers have been intensively investigated for fabricating high-performance macrofibers. Nanofibrillated cellulose (NFC) and cellulose nanocrystals (CNC) obtained from plants and bacterial cellulose (BC) nanofibers obtained via bacterial fermentation represent a remarkable class of nature-derived nanofibers with superior intrinsic mechanical properties owing to their high degree of polymerization and crystallinity. These features make them promising candidates for the development of mechanically robust, sustainable and biocompatible materials for diverse applications. Bio-sourced nanocellulosic materials, the most abundant raw material systems on earth, have attracted tremendous scientific and commercial attention recently due to their attractive combination of many inherent merits in terms of biodegradability, low density, thermal stability, global availability from renewable resources, as well as impressive mechanical properties. High-performance biomass-based nanocomposites are emerging as advanced renewable and sustainable materials for future structural and functional applications. This bioinspired design strategy provides a potential platform for further optimizing or creating many more strong and tough nanocomposite fiber materials for diverse applications. The achievement certifies the validity of the bioinspired hierarchical helical and nanocomposite structural design proposed here. By combining a facile wet-spinning process with a subsequent multiple wet-twisting procedure, we successfully obtain biomimetic hierarchical helical nanocomposite macrofibers based on bacterial cellulose nanofibers, realizing impressive improvement in their tensile strength, elongation and toughness simultaneously. ![]() Inspired by the widely existed hierarchical helical and nanocomposite structural features in biosynthesized fibers exhibiting exceptional combinations of strength and toughness, we report a design strategy to make nanocellulose-based macrofibers with similar characteristics. However, nearly all of them have been achieved at the expense of their elongation and toughness. Various strategies have been pursued to gain nanocellulose-based macrofibers with improved strength. Bio-sourced nanocellulosic materials are promising candidates for spinning high-performance sustainable macrofibers for advanced applications.
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