Preparation and performance of erasable photochromic ink based on acrylic copolymer

Writing has occupied major part of human’s daily activities in recent decades and inks are the most important tools for this reason. Water-based inks have specifically been attractive nowadays, because of health and environmental issues. In this work, an acrylic copolymer containing spiropyran ethyl acrylate (SPEA), as a photoactive monomer, was prepared by semi-continuous emulsion polymerization. Photochromic SPEA undergoes reversible isomerization between non-polar, colorless spiropyran (SP) and polar, colored merocyanine (MC) isomer upon visible light and UV irradiation at 365 nm. Hence, a smart ink including the above copolymer was formulated and it became pale purple after UV irradiation and changed to colorless form under visible light at ambient condition. Also, optical and morphological properties of the prepared copolymer were evaluated by UV-Vis spectroscopy and DLS analysis, respectively. Moreover, some tests were conducted to check the ink performance on cellulosic papers.

Spiropyran- Emulsion- Photochromic- Acrylic- Ink.