Li Dong, Yuan Jun, Cheng Qaoyun, Wei Peng, Cheng Gary J, Chang Chunyu
College of Chemistry and Molecular Sciences, Engineering Research Center of Natural Polymer-based Medical Materials in Hubei Province, and Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan, 430072, China.
Nanoscale. 2021 Jul 15;13(27):11808-11816. doi: 10.1039/d1nr01777b.
The assembly of cellulose nanocrystals (CNCs) that produce attractive structural color shows great potential in anti-counterfeiting application, but their processability and recyclability remain unsatisfactory due to the strong hydrogen bonds between CNCs. For the first time, optical anti-counterfeiting patterns are obtained by additive printing of surface-functionalized CNC inks (CNC-DC5700-NPES). The surface-functionalized CNC inks are prepared by sequential modification of CNCs with organosilane (DC5700) and polyoxyethylene ether (NPES), which show good flowability under shearing force and transform into a gel-like phase rapidly after printing, making possible ink-jet printing without additives. The printed patterns are transparent under natural light but show vivid interference color, showing anti-counterfeiting features between crossed polarizers. The texture and optical properties of the printed patterns can be facilely controlled by tuning the printing parameters, such as nozzle diameter, writing angle, and filling width. Moreover, the CNC-DC5700-NPES patterns with a core-shell structure could be collected in various solvents and reprinted after removing solvents. This work provided a new pathway for the preparation of optical anti-counterfeiting patterns from biomass resources.
能够产生引人注目的结构色的纤维素纳米晶体（CNCs）组装体在防伪应用中显示出巨大潜力，但由于CNCs之间存在强氢键，其可加工性和可回收性仍不尽人意。首次通过表面功能化的CNC油墨（CNC-DC5700-NPES）的添加剂印刷获得了光学防伪图案。表面功能化的CNC油墨是通过用有机硅烷（DC5700）和聚氧乙烯醚（NPES）对CNCs进行顺序改性制备的，它们在剪切力作用下表现出良好的流动性，并在印刷后迅速转变为凝胶状相，使得无需添加剂即可进行喷墨印刷成为可能。印刷图案在自然光下是透明的，但在交叉偏振器之间显示出鲜艳的干涉色，呈现出防伪特征。通过调整印刷参数，如喷嘴直径、书写角度和填充宽度，可以轻松控制印刷图案的纹理和光学性能。此外，具有核壳结构的CNC-DC5700-NPES图案可以在各种溶剂中收集，并在去除溶剂后重新印刷。这项工作为从生物质资源制备光学防伪图案提供了一条新途径。
