Solvent-Directed Morphogenesis of Conjugated Oligomer Supramolecular Assemblies Enabling Dual-Wavelength Photothermally Actuated Smart Devices

The regulation of the light absorption properties of organic photothermal drive materials needs to be achieved through extremely complex molecular structure engineering. This study proposes a newly solvent-directed coassembly strategy to achieve morphological control of conjugated oligomer nanostructures for fabrication of dual-band photothermal actuators. By coassembling the newly synthesized conjugated oligomer PDBTF with amphiphilic block copolymer PS-b-PAA, the transformation from spherical assemblies to needle-like rod-shaped nanoassemblies can be achieved by fine-tuning the ratio of the mixed solvent THF/MeOH. As the molecular packing order within the nanoassemblies was effectively modulated, the obtained nanostructures exhibit unique morphology-dependent optical absorption properties in the visible light band. Notably, these nanoassemblies were integrated into silicone rubber matrices, enabling mutiwavelength actuation. Under alternating 520/630 nm laser irradiation, the composite actuator achieves programmable rolling locomotion driven by asymmetric photothermal expansion. The nanoscale morphological controlling strategy based on solvent-modulated conjugated molecule supramolecular assembly opens avenues for advanced soft robotics manufacturing materials.