Preparation of cellulose colloidal particles in aqueous solution with good photochromic and photoluminescent performances by grafting a spiropyran derivative onto filter paper cellulose

The cellulose colloidal particles with good photochromic and photoluminescent performances had been developed in aqueous solution based on a spiropyran-grafted filter paper cellulose (SP–cellulose) in this study. The insoluble filter paper cellulose dramatically became soluble in ethanol after grafting a spiropyran derivative onto its backbone via esterification. During this process, the optical properties of the spiropyran had been successfully inherited. With the aid of ultraviolet and visible light, the obtained SP–cellulose colloidal particles showed light-induced tunability on both photochromism and photoluminescence, corresponding to the significant change of the spiropyran between weak polar ring-closed spiropyran and strong polar ring-opened zwitterionic merocyanine. Based upon this result, the SP–cellulose colloidal particles were finally obtained in water by follow-up dialysis process. In comparison to the pure spiropyran showing poor optical properties in mixed solvent of ethanol/water, the obtained SP–cellulose colloidal particles in water showed good photochromic and photoluminescent performances as well as fine stability. Considering also the raw material of filter paper being cheap and easy to get as well as the facile preparation process of the functional colloidal particles, our experimental results may bring about more promising applications of spiropyran species and water-insoluble cellulose in aqueous medium.