Near‐Infrared Light/Thermal Dual‐Responsive Epoxy‐Based Polydiacetylene Composite for 3D Printing

Abstract Polydiacetylene (PDA) is a promising material due to the chromatic transition through external stimulus. However, near‐infrared (NIR) light is on the periphery of attention to achieve the colorimetric change. Herein, an epoxy‐based PDA composite is prepared through a dual‐wavelength orthogonal photopolymerization strategy where 405 nm light and UV light are utilized in turn. The appearance of blue phase indicates that ene–yne‐conjugated PDA backbone is successfully formed in the composite. The generated PDA composite exhibits a blue‐to‐red color change upon heating. More interestingly, the fast chromatic transition is also observed under a laser diode at 1064 nm irradiation in the presence of a NIR dye (IR 1064). And such NIR light responsiveness of the composite upon NIR light irradiation is demonstrated by thermal imaging camera. Finally, the 3D printing technique is applied to the composite and the fabricated 3D pattern exhibits dual colorimetric transition in response to both heat and NIR light stimuli. Therefore, the newly proposed approach finds great applications in functional materials due to the unique dual thermal or NIR light stimuli responsiveness.