Contribution of Hydrogen-Bond Nanoarchitectonics to Switchable Photothermal-Mechanical Properties of Bioinorganic Fibers

Stimuli-responsive materials hold great potential for the development of smart materials due to their specifically tailored characteristics. However, it is challenging to understand internal molecular dynamics when the macroscopic mechanics of materials change in response to specific applied stimuli. Herein, we present the biological composite fibers of which mechanical properties can be reversibly controlled on demand by photothermal effect of an alternating near-infrared light irradiation. In stark contrast to the weakening of the mechanical properties of conventional materials by heating, the mechanical performance of the obtained fibers are significantly enhanced, showing an increase of Young's modulus by a factor of four. The outstanding photothermal-mechanical behavior relies on the evolution of hydrogen bonds within the system. We envision that this type of fiber material will inspire a new strategy for the construction of smart devices.