Zhou Fan, Liang Dingli, Liu Si, Guo Zeying, Wang Min, Zhou Gang
Laboratory of Advanced Materials, State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 2205 Songhu Road, Shanghai 200438, P.R. China.
ACS Appl Mater Interfaces. 2023 Oct 25;15(42):49418-49426. doi: 10.1021/acsami.3c09595. Epub 2023 Oct 16.
Digital inkjet printing has become one of the most convenient and efficient technologies for coating chromic materials on flexible substrates with complicated patterns. However, the development of water-based, additive-free chromic inks for inkjet printing still remains a challenge. Herein, three ammonium-functionalized colorless viologen derivatives , , and with excellent water solubilities are utilized as chromes in the chromic inks due to their excellent photochromic and electrochromic properties. Water, ethanol, and ethylene glycol are selected as cosolvents, and their contents in this ternary solvent system have been optimized to achieve comprehensive rheological properties. With the HO:EtOH:EG weight ratio of 8:1:7, the chromic ink based on realizes a viscosity of 4.69 mPa·s, a surface tension of 45.13 mN/m, and a value of 3.87. Without adding any additive, the as-prepared chromic inks can be printed on flexible substrates, such as paper and poly(ethylene terephthalate) (PET) films, by a conventional inkjet printer with inherent high resolutions. The printed patterns are initially invisible due to the colorless characteristics of the chromic inks. Interestingly, the printed films are responsive to both light and electric stimuli. Upon irradiation by UV light, a series of sentences with font sizes from 5 to 12 points and four quick response codes with different lattice resolutions clearly appear on the printed paper. Meanwhile, after printing on an indium tin oxide-coated PET substrate, electrochromic devices (ECDs) can be facilely fabricated by covering a hydrogel electrolyte on the printed films. Upon application of different potentials, the assembled ECDs exhibit "Peking Opera facial makeup" patterns with different colors. Therefore, the developed water-based additive-free chromic inks can be utilized for information display and encryption applications.
数字喷墨印刷已成为在具有复杂图案的柔性基板上涂覆铬材料最便捷高效的技术之一。然而，开发用于喷墨印刷的水基、无添加剂的铬墨仍然是一个挑战。在此，三种具有优异水溶性的铵官能化无色紫精衍生物 、 和 因其优异的光致变色和电致变色性能而被用作铬墨中的铬成分。选择水、乙醇和乙二醇作为共溶剂，并对它们在该三元溶剂体系中的含量进行了优化，以实现综合流变性能。当水：乙醇：乙二醇的重量比为8:1:7时，基于 的铬墨粘度为4.69 mPa·s，表面张力为45.13 mN/m， 值为3.87。在不添加任何添加剂的情况下，所制备的铬墨可以通过具有固有高分辨率的传统喷墨打印机印刷在柔性基板上，如纸张和聚对苯二甲酸乙二酯（PET）薄膜。由于铬墨的无色特性，印刷图案最初是不可见的。有趣的是，印刷薄膜对光和电刺激都有响应。在紫外光照射下，一系列字号从5到12磅的句子和四个具有不同点阵分辨率的二维码清晰地出现在印刷纸上。同时，在氧化铟锡涂层的PET基板上印刷后，通过在印刷薄膜上覆盖水凝胶电解质可以轻松制备电致变色器件（ECD）。施加不同电位时，组装好的ECD呈现出不同颜色的“京剧脸谱”图案。因此，所开发的水基无添加剂铬墨可用于信息显示和加密应用。
