Rewritable Polymer Materials for Ultraviolet Laser Based on Photochromic Microcapsules

Stimuli-responsive materials such as photochromic materials have attracted wide attention for their potential applications in anticounterfeiting, optical information storage, and photoswitching systems. Herein, we provided an approach to fabricate rewritable polymer materials based on photochromic microcapsules using an ultraviolet (UV, λ = 355 nm) pulsed laser. Due to the isomerizations of photochromic molecules being restricted by a lattice structure in solid state, microcapsules with a photochromic liquid core (PCLC) and melamine-formaldehyde (MF) shell were developed as the photochromic component. SEM and TEM confirmed the core–shell structure, and the typical thickness of the shell was 0.20–0.26 μm. PCLC@MF microcapsules were further integrated into a polydimethylsiloxane (PDMS) flexible matrix. The reversibly photochromic property of this microcapsule-embedded composite was characterized by colorimetric data and UV–vis spectroscopy. The rewritable feature of the PDMS composite was tested in UV and visible light cycles. Moreover, unique matte patterns were fabricated on the surface of the obtained PDMS composite using a UV pulsed laser tunably and efficiently. By altering laser parameters, color shades of patterns could be easily regulated. Because microcapsules determined the photochromic function, this method was suitable for most polymer matrices via laser direct writing.