Dual-bionic, fluffy, and flame resistant polyamide-imide ultrafine fibers for high-temperature air filtration

Particulate matter (PM) pollution has been acknowledged as a serious health hazard globally, calling for thermo-stable air filtration materials to remove particles from high-temperature emission sources. However, the commercial filter media suffer from large fiber diameter and compact assembling architecture, resulting in the difficulty in achieving a balance between filtration efficiency and pressure drop. Herein, a dual-bionic strategy is proposed to prepare high-performance polyamide-imide (PAI) fibrous assemblies for the application in high-temperature air filtration. Inspired by the fact that Masson Pine shows attractive capability of particle retention, PAI fibers with biomimetic groove structure are constructed via asynchronous phase separation principle, meanwhile showing fluffy assembling architecture via humidity-induced electrospinning technology. Furthermore, the stiff cellulose networks within loofah sponges, which contributes to robust mechanical property, inspired us to construct semi-interpenetrating polymer network (semi-IPN) structure within PAI fibers. Benefitting from the hierarchical structure and intrinsic flame resistant property, the resulting PAI ultrafine fibers present distinct characteristics of high specific surface area (25.97 m2/g) and high porosity (90.44 %), contributing to a high PM2.5 filtration efficiency (98 % at severe pollution), a low pressure drop (only 46.35 Pa), and satisfying long serving time at 220℃. The successful fabrication of PAI filter media brings new insights for designing next-generation thermo-stable air filters.