Butterfly Wing Microstructure Inspired Solid/Porous Alternating Layered Structures: In Situ Visualization of Confined Foaming

This study explores confined foaming in micro‐/nano‐layered (MNL) solid/porous alternating structures inspired by the hierarchical architecture of Ulysses butterfly wings. Biomimetic MNL films composed of alternating polycarbonate (PC) and polymethyl methacrylate (PMMA) layers (17–513 layers) are fabricated via advanced coextrusion and foaming techniques. In situ visualization reveals confinement effects dependent on layer thickness; while nucleation primarily occurrs at PC/PMMA interfaces due to reduced energy barriers, a strong confinement zone within 10 µm of the interfaces significantly restricts cell growth, most notably in the 129‐layer and 513‐layer samples, where single‐cell rows are observed. Thermal regulation tests show that the 513‐layer bio‐mimic structure reduces temperature rise by 80%, 65%, and 50% compared to polyethylene (PE) film, a three‐layer sandwich structure, and butterfly wings, respectively. It also exhibits exceptional delay in heat accumulation under radiative conditions, with a time to reach half of the maximum temperature rise of 165 s, compared to 20 s (PE) and 40 s (both three‐layer and butterfly wing). The bio‐mimic architecture also exhibits strong anisotropic thermal conductivity, effectively suppressing through‐thickness heat transfer while enhancing lateral dissipation. These results connect nature‐inspired design and practical implementation, highlighting the potential of bio‐mimic MNL structures for advanced thermal management applications.