Rewritable Polymer Materials for Ultraviolet Laser Based on Photochromic Microcapsules

Abstract

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.

Quadri-Dimensional Anti-counterfeiting Flexible Label Programmed by a Photoresponsive Liquid Crystal Polymer Film

“…The widespread counterfeiting of banknotes, certificates, brands, pharmaceuticals, and jewelry has become a serious worldwide problem because of its harmful effects on the global economy, security, and health. − Developing anti-counterfeiting materials is highly desirable to increase the level of security. , Over the past few decades, various macroscopic patterns have been developed to prevent counterfeiting and information leakage, including watermarking, holograms, barcodes, and QR codes. − However, these strategies are relatively changeless and easy to copy . Therefore, photoresponsive materials have attracted accumulated attention due to their variable color or fluorescence triggered by light, − providing tremendous potential for information encryption. , Among these photoresponsive systems, liquid crystal (LC) performs excellently in tunability and responsiveness .…”

Preparation of Photochromic Microcapsules of Poly(methyl methacrylate)/Inorganic Metal Oxide Composite Shells with UV‐Resistant Properties and Application to Printing on Cotton Fabrics

“…[6,7] Upon removal of the light source, the compound gradually reverts to a colorless pyran structure. [8,9] However, spiropyran compounds are susceptible to oxidative fission [10] and fatigue due to their sensitivity to UV rays, temperature, and other environmental factors. [11] These limitations hinder their application in fields such as textiles.…”