Photothermal Dual‐Responsive Naphthoxazine Enables Integrated UV‐Shielding, Blue‐Light Blocking, and Fire‐Resistant Polymer

Abstract Over‐exposure to harmful lights and the increasing fire risks are driving a pressing need for multifunctional protective materials. However, most methods rely on the physical superposition of various functional additives, raising health concerns about the additives and global environmental issues. Herein, a “kill three birds with one stone” efficient strategy is proposed to construct UV‐shielding, blue‐light blocking, and fire‐resistant polymer through photothermal dual‐responsive naphthoxazine unit. When exposed to UV (100–400 nm) and harmful blue light (400–455 nm), the photoresponsive naphthoxazine absorbs these high‐energy rays and then converts light energy into heat. Under the high temperature of fire, the thermally responsive naphthoxazine undergoes chemical ring‐opening crosslinking, thereby increasing the melt viscosity and char‐forming ability of the polymer material. With only 4.76 mol% of naphthoxazine unit, the corresponding polymer exhibits excellent 100% shielding of the UV rays, 100% blocking of harmful blue light, and the best flame‐retardant UL‐94 V‐0 rating with nondripping. This work simultaneously integrates three advanced functions through a single naphthoxazine unit, achieving previously unattainable personnel safety protection against harmful light and dangerous fire.