Smart Surfaces with Photothermally Switchable Topography

Here, we report smart, photothermal, remotely reversibly controllable, high-aspect-ratio lamellar structures fabricated by melt electrowriting (MEW) using a polyester urethane based on poly(1,10-decylene adipate) incorporating 0.2 wt % graphene nanoplates (GNP) or multiwalled carbon nanotubes (MWCNT). The addition of these carbon-based fillers enables efficient photothermal conversion under near-infrared (NIR) laser irradiation, allowing localized heating of individual lamella. As a result, reversible buckling of the lamellar structures is achieved through the melting of the soft segments, enabling tunable interlamellar spacing and programmable topography. Moreover, the direction of bending can be guided by the capillary forces applied within the interlamellar space─by applying a water droplet. The switchable lamellar topography enables displacement of droplets and their controlled merging within a single interlamellar groove, which is demonstrated using FeCl3 and K4[Fe(CN)6] solutions, leading to the formation of Prussian blue crystals upon contact. This remotely controlled, light-responsive smart lamellar architecture provides promising applications in microfluidics, smart surfaces, and soft robotic systems.