Synthesis of Azobenzene Grafted Poly(ionic liquid)s and Its Multifunctional Optical Applications
Three kinds of poly(ionic liquid)s(PIL-Azo-x)with different grafting ratios of azobenzene(10％,30％,and 50％)were successfully synthesized by using conventional free radical polymerization and post-polymerization modification strategies.The initial decomposition temperatures of PIL-Azo-x were higher than 300 ℃,indicating good thermal stability.The films prepared by simple casting method exhibited excellent UV shielding performance in the 200-400 nm band,which can block almost all UV rays;in the 400-600 nm band,they have tunable transmittance performance,which can be reversibly changed under the irradiation of 365 nm UV and 450 nm visible light,and the transmittance decreases accordingly with the increase of the content of azobenzene;in the 600-800 nm band,they show a high transmittance performance,which can be reversed with an increase in the content of azobenzene.In addition,the pure PIL-Azo-x casted films have excellent acid and alkali resistance,and the transmission spectra of the films remain almost unchanged after immersion in a pH=2 HCl solution or pH=12 NaOH solution for 6 h,which makes them suitable for the more severe environments.Finally,its application in the field of pattern writing and erasing is demonstrated in combination with the mask plate method,in which the transparent film can be repeatedly customized with different patterns under the irradiation of 365 nm UV light and 450 nm visible light.These poly(ionic liquid)films with strong UV shielding,tunable transmittance,high transparency,good thermal stability,and excellent acid-base stability are expected to contribute to the development of multifunctional optical coatings,smart windows,and other fields.
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