Wenshuo Zhang,Tao Zhang,Yajun Deng,Zhihao Guan,Yuye Zhong,Shuliang Fang,Guannan Wang,Xinghai Liu,Houbin Li
Recent research is keen to introduce biomass materials into inks to develop "green” printing, but little attention has been given to whether these inks can be truly widely used in printing industry. There are few bio-based inks suitable for low surface energy plastic such as polyethylene glycol terephthalate (PET), which is one of the most common printing substrates. Herein, waterborne polyurethane with polyfluoroalkyl side chain (F-WPU) was designed and synthesized to prepare fluorocarbon quantum dots (F-CDs). F-WPU and F-CDs were mixed together with gelatin to obtain environmentally friendly inks which were utilized to print on a low surface energy substrate. F-WPU (30 wt%) and F-CDs (0.5 wt%) significantly improve the mechanical properties of composites by forming an interpenetrating network system and hydrogen bonds , respectively. Abundant carbon-fluorine bonds effectively reduce the surface energy of gelatin, resulting in excellent hydrophobicity and strong adhesion to the PET surface. The thermal stability of the composite could significantly enhance to meet the promising needs for the further engineering applications . Besides, F-CDs could emit blue-green fluorescence based on conjugated structure and π→π* transition under a wider excitation wavelength. Therefore, the complex exhibited good transparency under sunlight and performed significant cyan fluorescence under an ultraviolet irradiation, in which can be efficiently developed and used in anti-counterfeiting labels and printing. Furthermore, the friction, soaking and kneading tests have been measured to seriously take the considerations for the stable dry and wet fastness for the PET films, which could industriously expand the ink applications.
Rapidly responsive and flexible photonic papers are manufactured by coassembly of cellulose nanocrystals (CNCs) and waterborne polyurethane (WPU) latex for fully taking advantage of the chiral nematic structure of CNCs and the flexibility of WPU elastomer. The resulting CNC/WPU composite papers exhibit not only tunable iridescent colors by adjusting the helical pitch size, but also instant optical responses to water and wet gas, ascribed to the easy chain movement of the elastomeric WPU that does not restrict the fast water absorption-induced swelling of CNCs. By choosing water or NaCl aqueous solutions as inks, the colorful patterns on the CNC/WPU photonic paper can be made temporary, durable, or even disguisable. In addition, the photonic paper is simultaneously rewritable for all these three types of patterns, and the disguisable patterns, which are invisible at normal times and show up under stimuli, exhibit a quick reveal conversion just by exhaling on the paper. The rewritability, rapid responsibility, easy fabrication, and the eco-friendly nature of the inks make the flexible photonic paper/ink combination highly promising in sensors, displays, and photonic circuits.
危险品化学品经营许可证（带存储）