Translucent and Anti-ultraviolet Aramid Nanofiber Films with Efficient Light Management Fabricated by Sol–Gel Transformation

Abstract

Derived from poly­(para-phenylene terephthalamide) PPTA fibers, aramid nanofibers (ANFs) not only inherit the excellent properties of PPTA fibers but also demonstrate the nanoeffects of one-dimensional (1D) nanomaterials, showing great potentials in many emerging fields as building blocks. However, ANF-based materials are usually obtained by vacuum-assisted filtration after the regeneration of ANFs, leading to long cycle times and waste of energy. Moreover, the effects of antisolvents on the structure and property of the obtained ANF-based materials were rarely reported. In this work, an in situ-regenerated continuous production line of sol–gel transformation technology was provided to produce ANF films in a large scale. Moreover, the impacts of coagulation baths (water and ethanol) on the structure and properties of ANF films were investigated systematically. It was found that the coagulation baths had obvious effects on the microstructure and properties of ANF films. As a result, ANF films with high transparency, high anti-ultraviolet capacity, and tunable haze can be fabricated successfully by simply changing the component of the coagulation bath. Particularly, the averaged values of ANF films in the region of 315–400 nm (TUVA) and 290–315 nm (TUVB) are nearly 0%, and the haze of ANF Film 100 can reach as high as 90% at 800 nm when ethanol was used as the first coagulation bath. Meanwhile, ANF films (Film 0) regenerated from water displayed the highest transmittance (78.77% at 800 nm) and tensile strength (102.88 MPa), attributed to their homogeneous structures. Additionally, the transmittance and tensile strength were decreased obviously with the increasing ethanol content in the first coagulation bath. Overall, ANF films showed high tensile strength, good thermal stability, and fire-retardant performance. Herein, the ANF films with many merits demonstrate great promising potential to be used in the light management field