Biomimetic Hierarchical Textiles with Spontaneous Liquid Directionality and Radiative Cooling for Personal Thermal Management

Integrating zero-energy cooling technology into personal thermal management (PTM) systems offers an effective approach to prevent heat-related illnesses and reduce energy consumption. Although materials designed for passive radiative cooling have been introduced, achieving an optimal balance between cooling efficiency and user comfort continues to pose a significant challenge. Here, we present a biomimetic personal thermal management (BPTM) fabric that couples passive radiative cooling with transpiration-like evaporative cooling through a hierarchical trilayer polymer architecture. The top layer consists of an electrospun cellulose acetate (CA) nanofibrous photonic coating loaded with Al2O3 nanoparticles, providing strong solar back scattering and (mid-infrared MIR) emission via the intrinsic vibrational bands of CA. A middle porous layer composed of polyurethane (PU)/CA establishes a wettability and pore-size gradient for self-driven, outward liquid transport. The bottom layer is a waterborne polyurethane (WPU) fabric substrate that imparts flexibility and wearer comfort. Owing to this trilayer design, the BTPM fabric exhibited favorable spectral selectivity, with around 92% sunlight reflection and 96% thermal emissivity in the atmospheric window. It also demonstrated Janus wettability (R = 340), achieved through electrospinning and hierarchical design, while maintaining superior moisture permeability. Temperature reductions of approximately 10 °C were observed in the BPTM fabric compared to that of commercial cotton. The fabric’s moisture-wicking properties (water evaporation rate of 0.21 g h–1) facilitate rapid sweat evaporation, cooling the skin so as to minimize the possibility of excessive sweating when exercising. Moreover, the fabric’s cost-effectiveness and wearability offer a promising direction for sustainable energy solutions, smart textiles, and applications focused on thermal comfort.