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The application of natural small molecule (NSM) in electrospun fibers is the key to achieving powerful functionality and sustainable development. However, the lack of understanding regarding the mechanism for loading NSM hinders the advancement of high-performance functional fibers. This work clarified the loading mechanism of NSM in polymer solution by comparing the different behaviors of curcumin (Cur), phloretin (PL), and tea polyphenols (TP) blended ethyl cellulose (EC) solutions. We found that TP may lead to the folding of polymer chains due to its strongest hydrogen bond, which in turn promoted the dispersion of TP along the polymer chain. Therefore, TP could achieve good electrospinnability at the highest loading capacity (16 times the Cur and 4 times the PL). Finally, chitosan was introduced into EC/TP to prepare tree-like nanofibers, achieving high-performance antibacterial air filtration. The filtration efficiency for 0.3 μm NaCl particles, pressure drop, and quality factor were 99.991 %, 85.5 Pa, and 0.1089 Pa -1 , respectively. The bacteriostatic rates against Escherichia coli and Staphylococcus aureus were all 99.99 %. This work will promote the application of NSM and the developments of multifunctional electrospun fibers and high-performance air filters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Functionalization of bio–based nanofibers is the development tendency of high–performance air filter. However, the conventional structural optimization strategy based on high solution conductivity greatly hinders the development of fully bio–based air filter, and not conducive to sustainable development. This work fabricated fully bio–based nanofibrous membrane with formaldehyde–adsorbable and antibacterial capabilities by electrospinning low–conductivity solution for high–performance air filtration and applied to lightweight mask. The "water–like" ethyl cellulose (EC) was selected as the base polymer to "nourish" functional materials of gelatin (GE), β–cyclodextrin (βCD), and curcumin (Cur), thus forming a solution system with high binding energy differences and electrospinning into ultrafine bimodal nanofibers. The filtration efficiency for 0.3 μm NaCl particles, pressure drop, and quality factor were 99.25 %, 53 Pa, and 0.092 Pa−1, respectively; the bacteriostatic rates against Escherichia coli and Staphylococcus aureus were 99.9 % and 99.4 %, respectively; the formaldehyde adsorption capacity was 442 μg/g. This is the first report on antibacterial and formaldehyde–adsorbable high–performance air filter entirely made from bio–based materials. This simple strategy will greatly broaden the selection of materials for preparing high–performance multifunctional air filter, and promote the development of bio–based air filter. [Display omitted] [ABSTRACT FROM AUTHOR]

Functionalization and lightweighting of high-performance air filters can markedly improve quality of life. However, achieving this goal with green processes and fully bio-based materials remains challenging, placing significant strain on the environment and energy resources. The key lies in mastering the appropriate material matching strategy and its mechanism for the forming of membrane structure. Here, ethyl cellulose (EC)/tea polyphenol (TP)/betaine (BT) bimodal nanofibrous membranes were fabricated by blended electrospinning using green solvents. The synergistic interaction between TP and BT termed the "small molecule mutual support mechanism", is particularly compelling. TP could prevent polymer chains from being difficult to deform because of BT, making it good spinnable even under high BT loading. In this case, the cations of BT were sufficient to cause jet splitting, forming a bimodal structure. Consequently, high-performance antibacterial air filtration had been achieved under ultra-light and ultra-thin conditions (15% and 8% of N95 masks, respectively). The filtration efficiency for 0.3 μm NaCl particles, pressure drop, and quality factor were 99.79%, 58.7 Pa, and 0.1050 Pa-1, respectively. The antibacterial rates for Escherichia coli and Staphylococcus aureus were all 99.99%. This study offers insights into the green and sustainable design of advanced protective equipment. [Display omitted] • High-performance air filter fabricated based on green and renewable materials. • Micro dynamic behavior of electrospinning jet has been innovatively interpreted. • Light-weight, high-performance and antibacterial air filtration has been achieved. • Air filtration membrane was entirely composed of bio-based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication strategy inspired by nature mutualism was used. • Optimization of essential oil in preparation of high-performance air filter. • CMA and PHMB work together to achieve functionalization and fiber refinement. • Biopolymer–based air filtration membrane was prepared by one-step electrospinning. • High–performance air filter with antibiosis and mosquito repellent was realized. Composite bio–based multifunctional air filtration is a great challenge and development trend for personal protection. This work was inspired by nature mutualism to produce bio–based and essential oil loaded nanofibrous membrane with multiple functions of high–performance, antibacterial, and mosquito–repellent. The cinnamaldehyde (CMA) and poly(hexamethylene biguanide) (PHMB) were introduced into the cellulose acetate (CA) polymer system to achieve functionalization, and then the CA/CMA/PHMB ultrafine bimodal nanofibrous membrane was prepared through one–step electrospinning. Compared to eugenol, the CMA contributed to the refinement of fiber and minimized the reduction of mechanical properties, thermal stability, and hydrophobicity. On the other hand, the PHMB enhanced jet splitting and synergistically improved antibacterial ability with CMA. The filtration efficiency for PM 0.3 , the pressure drop, and the quality factor were 99.78%, 59.5 Pa, and 0.1028 Pa−1, respectively. The bacteriostatic rates against Escherichia coli and Staphylococcus aureus , and the mosquito–repellent rate were 99.65%, 99.99%, and 92.7%, respectively. Lastly, the batch preparation of this solution was explored, which contributed to commercialization. This work provides a novel and simple approach to efficiently fabricate multifunctional high–performance air filter, which will promote the development of bio–based and sustainable air filter. [ABSTRACT FROM AUTHOR]

[Display omitted] • Manufacturing strategy of electrospun bimodal fibrous membrane are summarized. • Characteristics and advantages of bimodal nanofibrous membrane are analyzed. • Multifunctional applications of bimodal air filtration membranes are listed. • Jet behavior in bimodal fibers electrospinning process is analyzed in detail. Electrospun nanofibrous air-filtration membranes, which are cost-effective materials that help safeguard human health, have garnered widespread attention. To comprehensively enhance the protection capabilities, comfort (for masks), energy efficiency (for air purifiers), and achieve optimal overall benefits, there is a demand for the functionalization and lightweighting of high-performance air filtration membranes. Bimodal nanofiber membranes can deliver high-performance air filtration with a higher proportion of fine fibers, contributing to a lightweight design. Moreover, they are compatible with various functionalization strategies. Therefore, an in-depth analysis of electrospun bimodal nanofibrous membranes is key to promoting the development of high-performance air filters. However, this has yet to be achieved. Importantly, deep-level mechanisms of the electrospun jet behavior are involved in the fabrication of bimodal structures. Reflection on these phenomena may guide theoretical and experimental studies in related fields, such as fluid dynamics and materials science. This study details electrospun bimodal nanofibrous membrane properties, high-performance air filtration mechanisms, fabrication methods, and molding mechanisms. Subsequently, the functionalized applications are summarized. Finally, the challenges encountered in the development of bimodal air filtration membranes are discussed. [ABSTRACT FROM AUTHOR]