High‐Dielectric‐Constant and Biodegradable Fiber Membrane for High‐Efficiency and Low‐Resistance Air Purification by the Interfacial Polarization Enhancement^†

Comprehensive Summary Polymer fiber filters play a vital role in removing particulate matter (PM), reducing environmental risk factors and cardiovascular diseases. However, the contradiction between high filtration efficiency and low airflow resistance limits the filtration performance of polymer filters, while exacerbating the microplastic contamination. Herein, we proposed an interface polarization strategy to fabricate a biodegradable fiber membrane with a high relative dielectric constant to filter the PM in a high‐efficiency and low‐resistance way. The membrane was constructed by silk fibroin (SF) and wool fiber membrane (Wool), where the SF bonded on the wool surface to form a crosslinked network. Specifically, polar groups (‐NH 2 /‐OH) on SF form a dynamic hydrogen‐bonding network with airborne water molecules, enhancing the interface polarization and elevating the relative dielectric constant to 8.4. Based on this high dielectric constant, Wool loaded with 20 mg of SF (SF@Wool) reaches PM 0.3 filtration efficiency of 99.69%, with air resistance of 8 Pa. Meanwhile, SF@Wool exhibits filtration efficiency decay of less than 0.5% over 30 d, demonstrating excellent long‐term stability. Furthermore, the biodegradable properties of SF@Wool effectively prevent microplastic pollution (it can be completely degraded in soil within 14 d after treatment with alkaline solution).