Bioinspired Multi-Gradient Structure Enables Environment-Adaptive Personal Respiratory Protection and Moisture Management for Biodegradable Poly(lactic acid) Meta-Membranes

Effective respiratory protection is crucial against airborne PM pollution and modern viral pandemics. However, conventional filters often exhibit poor moisture management, where exhaled vapor condenses within the mask microenvironment, compromising comfort and increasing breathing resistance due to liquid bridging. Herein, inspired by hierarchical porous architecture and amphiphilicity of diatom frustules, a biomimetic multi-gradient (BMG) strategy is proposed to engender poly(lactic acid) meta-membranes featuring an exceptional combination of efficient protective performance and superb moisture management. A hierarchical gradient structure comprising macroporous and microporous layers is constructed, mimicking the areola and cribrum structures of diatoms. By incorporating interfacial orientation factors, a progressive transition in wettability from hydrophobic to hydrophilic is achieved for the membranes, reproducing the wax-silanol-directed interfacial regulation mechanism of diatoms. Simultaneously, nanodielectrics dispersed by biotemplating effect emulated the metal-doped biosilica in diatoms to achieve charge confinement, enhancing charge trapping and storage capabilities of the membranes. The bioinspired meta-membranes demonstrated exceptional PM 0.3 filtration efficiency (96.26%), ultralow airflow resistance (40 Pa, 32 L min −1 ), and superior moisture permeability (WVTR: 223.5 g m −2 h −1 ), effectively facilitating the moisture wicking and long-term stability under high-humidity environments. This work offers a biomimetic paradigm for developing next-generation and eco-friendly protective materials with sustained comfort and high efficiency.