Preparation of a Cellulose Film Based on a Binary Thermoreversible Color-Changing System with Long-Chain Color Developers for Information Storage

Traditional printed paper, due to its irreversible chromogenic properties, is difficult to recycle. Thus, developing an ecofriendly storage carrier that allows for reversible information recording is one of the current research priorities. However, the thermal reversible information storage carriers reported so far have difficulty forming a stable structure, which limits their large-scale application. In this study, a novel color developer, 1-(4-hydroxyphenethyl)-3-octadecylurea (PCU), was synthesized using p-hydroxyphenylethylamine and octadecyl isocyanate. By combining it with fluoran dyes (FDs) and introducing natural cellulose as a binder resin, we successfully prepared a thermoreversible color-changing cellulose film with excellent color development performance. This film has a tensile strength of over 40 MPa and an elongation of over 10% and exhibited stable and efficient rewritable performance in 50 cycles of color development tests. Furthermore, it maintains a high color density for up to 20 weeks, and environmental factors such as temperature, humidity, and sunlight exposure have minimal effect on its color display and retention capabilities. Building upon this, application scenarios, such as ink-free stamping, thermal printing, and information encryption, have been further designed. The results show that the film's ink-free stamping is simple and effective, thermal printing patterns are clear, and information encryption is convenient and straightforward, demonstrating broad application prospects and providing a new approach to the fabrication of novel reversible information storage carriers.