Humidity/photothermal dual-responsive TpPa-SO3H/Ag@MXene actuator for intelligent thermal management

With the increasing severity of urban heat islands, personal thermal management (PTM) has emerged as a critical solution for maintaining human thermophysiological comfort in dynamic environments. Traditional air conditioning systems are energy-intensive and lack individualized control, highlighting the need for efficient, low-energy PTM strategies. Current PTM materials often operate in static modes, limiting their adaptability to varying conditions. To overcome this, we developed a Janus-structured humidity-photothermal actuator (TpPa-SO₃H/Ag@M) by integrating a TpPa-SO₃H covalent organic framework (COF) for rapid water transport and a silver nanoparticle (AgNP)-intercalated MXene (Ag@M) for humidity gradient formation and enhanced photothermal conversion. The COF layer facilitates moisture accumulation, while the Ag@M laminar structure delays water diffusion, enabling a sensitive humidity response. AgNPs expand the MXene interlayer spacing, improving water uptake and response efficiency by triple compared to initial TpPa-SO₃H/MXene systems, while also preventing structural collapse during cycling. Additionally, AgNPs enables strong solar absorption, boosting photothermal performance. Under combined humidity and light stimulation, the Janus actuator exhibits dynamic bending, enabling autonomous sweat evaporation and body temperature regulation without external energy input. This dual-responsive design offers a promising approach for adaptive, energy-efficient PTM in extreme environments.