Constructing extended conjugate structure at matrix-filler interface: Enabling photothermal elastomer with enhanced mechanical performance and light-to-thermal conversion efficiency

A persistent challenge in photothermal conversion elastomers (PTCEs) is simultaneously achieving high photothermal conversion efficiency and robust mechanical properties. Herein, an efficient strategy, constructing extended conjugate structure at the interface of matrix and filler, was developed. Specifically, caterpillar-like Janus particles (CJPs), composed of alternating 3-aminophenol-formaldehyde copolymer bulb and SiO 2 bulb, were first synthesized using an oil-water interface growth and assembly method. These CJPs were then integrated into an aqueous polyurethane matrix through imine bond that was formed by the condensation of amine group on the particle and aldehyde group on the matrix. Interestingly, the interfacial imine bonds are playing three roles, i.e. , facilitating uniformly dispersing of the fillers, bridging the benzene rings existing in the matrix and the filler, and endowing the PTCEs with self-repairing properties. Consequently, the obtained PTCEs exhibited both excellent mechanical properties (tensile strength of 29.63 MPa and elongation at break of 1602%) and high photothermal conversion efficiency (86.79%). This synergistic performance enables the PTCEs to act as next-generation solutions for practical applications including photothermal generators and reversible adhesive tapes. In general, this work not only establishes a new application direction for the Janus particles, but also provides a design guideline for high-performance of PTCEs.