Surface Grafting of Paper with Photochromic Spiropyran Ether Methacrylate

Abstract

It was demonstrated that a photochromic paper could be made through the atom transfer radical polymerization (ATRP) method by grafting spiropyran ether methacrylate (SPMA) onto the fiber surface. The surface composition and topography of the grafted paper were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectra (XPS), and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). Crystal structures of the cellulosic fibers were also examined after the grafting reaction. The characteristic absorption bands detected in the FTIR spectrum after grafting suggested that a new functional group was formed by the reaction. The XPS and SEM results confirmed that SPMA was grafted onto the surface of the fibers successfully. The grafted spiropyran groups exhibited reversible photochromic properties when exposed to UV light irradiation and visible light. The modified paper showed a purple color under UV light irradiation and changed back to its original color when exposed to visible light. This surface modification using ATRP was demonstrated to be a feasible way to prepare photochromic paper.

Fabrication of Robust Spatially Resolved Photochromic Patterns on Cellulose Papers by Covalent Printing for Anticounterfeiting Applications

“…The vast majority of published works report the preparation of photochromic papers using merocyanine dyes as photoactive compounds without any spatial control of the cellulose functionalization, excluding any molecularly imprinted patterns. − Moreover, when covalently anchored to the material surface, the photochromism of merocyanine dyes is frequently affected by the polar environment of the cellulose matrix as the colored open form is strongly stabilized within the hydrogen bond network of cellulose. , The irreversibility of the photochromism can be prevented through the impregnation of merocyanine dyes with a polymer carrier within the cellulose matrix, ,, but the creation of photochromic patterns through a spatial control of the functionalization is still not demonstrated through these studies.…”