Hierarchical Structured Polyimide–Silica Hybrid Nano/Microfiber Filters Welded by Solvent Vapor for Air Filtration

• Main Authors: Dawei Li, Ying Shen, Lanlan Wang, Feng Liu, Bingyao Deng, Qingsheng Liu
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Polymers
• Subjects: electrospinning; hierarchical structure; hybrid nano/microfiber filters; air filtration
• Online Access: https://www.mdpi.com/2073-4360/12/11/2494

Electrospun polymer membranes were considered to be promising materials for fine particulate matter (PM) filtration. However, the poor mechanical properties of the electrospun membrane restricted their application for pressure-driven air filtration. Herein, strength-enhanced electrospun polyimide (PI) membranes were demonstrated via a synergistic approach. Solvent-vapor treatment was utilized to introduce extra bonding at the cross points of PI nanofiber, while SiO₂ nanoparticles (SiO₂ NPs) were used to reinforce the body of nanofibers. The mechanical strength and filtration performance of hybrid membranes could be regulated by adjusting the quantity of SiO₂ NPs. The tensile strength of the pure PI membrane was increased by 33% via adding 1.5% SiO₂ NPs, which was further promoted by 70% after solvent-vapor treatment. With a slight reduction in pressure drop (6.5%), the filtration efficiency was not greatly suppressed by welding the SiO₂ NP hybrid PI nanofibers. Moreover, the welded composite filter showed high particulate (0.3–1.0 μm) filtration efficiency (up to nearly 100%) and stable pressure drop throughout the 20 tested filtration cycles.