Hierarchical Bio‐Composites With Nacre‐Inspired Interfacial Design for Durable Multifunctionality and Upcyclable Sustainability

ABSTRACT Biobased polylactic acid composites show great potential as alternatives to petroleum‐based polymer materials, but their practical use is limited by the difficulty of simultaneously achieving mechanical strength, service durability, and integrated functionality. To address this challenge, we developed a biomimetic interfacial engineering strategy inspired by nacre's rigid‐inorganic/flexible‐organic interfacial composition. The composite exhibits favorable mechanical strength (flexural strength increased by 3.8 times) and durability under harsh environments, and outstanding UV‐blocking properties are imparted by the interior of the composite together with its biomimetic interfacial layer, effectively inhibiting the photodegradation of various water‐soluble organic substances (degradation extent <6%). The composite also features ultrahigh solar absorption (>95%), enabling efficient outdoor deicing/snow removal and stable solar‐driven desalination, combining high evaporation efficiency (>94%) with excellent cycling stability. More significantly, at the disposal stage, the porous and surface‐functionalized residue can adsorb dyes and heavy‐metal ions from water, supporting resource‐oriented end‐of‐life utilization. The composite also shows antifungal rates exceeding 96%, long‐term antifungal behavior, low toxicity in the tested aquatic plant system, and soil‐burial degradation behavior. This work presents an interfacial‐design route for high‐strength, multifunctional, and recyclable bio‐based composites for outdoor and water‐treatment‐related applications, which is anticipated to exhibit significant potential in sustainable polymer materials.