Neterebskaia Valeriia O, Goncharenko Anna O, Morozova Sofia M, Kolchanov Denis S, Vinogradov Alexandr V
Inkjet printing group, International Institute "Solution Chemistry of Advanced Materials and Technologies" (SCAMT), ITMO University, 191002 Saint Petersburg, Russia.
Nanomaterials (Basel). 2020 Aug 5;10(8):1538. doi: 10.3390/nano10081538.
This study is devoted to the development of photonic patterns based on polystyrene spheres (PSS) incorporated in chitosan hydrogels by inkjet printing. Using this method, high-resolution encrypted images that became visible only in high humidity were obtained. Inks based on PSS with carboxylic groups on the surface were made, and their rheological parameters (viscosity, surface tension, and ζ-potential) were optimized according to the Ohnesorge theory. The obtained value of the ζ-potential indicated the stability of the synthesized colloidal inks. The dependences of the printing parameters on the concentration of ethylene glycol in PSS dispersion, the drop spacing, the shape of the printed pattern, waveform, the temperature of the printing process, and the degree of ordering of the PSS-based photonic crystal were investigated. The scanning electronic microscope (SEM) images confirmed that the optimal self-organization of PSS was achieved at the following values of 0.4% weight fraction (wt%) carboxylic groups, the drop spacing of 50 μm, and the temperature of the printing table of 25 °C. High-resolution microstructures were obtained by drop-on-demand printing with a deposited drophead diameter of 21 μm and an accuracy of ±2 μm on silicon and glass substrates. The deposition of chitosan-based hydrogels on the obtained polystyrene photonic crystals allowed reversibly changing the order of the diffraction lattice of the photonic crystal during the swelling of the hydrogel matrix, which led to a quick optical response in the daylight. The kinetics of the appearance of the optical response of the obtained coating were discussed. The simplicity of production, the speed of image appearance, and the ability to create high-resolution patterns determine the potential applications of the proposed systems as humidity sensors or anticounterfeiting coatings.
本研究致力于通过喷墨打印技术，开发基于掺入壳聚糖水凝胶中的聚苯乙烯球体（PSS）的光子图案。使用这种方法，获得了仅在高湿度下才可见的高分辨率加密图像。制备了表面带有羧基的基于PSS的墨水，并根据奥内佐格理论优化了其流变参数（粘度、表面张力和ζ电位）。所获得的ζ电位值表明了合成胶体墨水的稳定性。研究了打印参数对PSS分散体中乙二醇浓度、墨滴间距、打印图案形状、波形、打印过程温度以及基于PSS的光子晶体的有序度的依赖性。扫描电子显微镜（SEM）图像证实，在羧基重量分数为0.4%、墨滴间距为50μm以及打印台温度为25℃的条件下，实现了PSS的最佳自组装。通过按需滴墨打印在硅和玻璃基板上获得了高分辨率微结构，沉积墨滴头直径为21μm，精度为±2μm。在所得聚苯乙烯光子晶体上沉积基于壳聚糖的水凝胶，使得在水凝胶基质膨胀过程中，光子晶体的衍射晶格顺序能够可逆地改变，从而在日光下产生快速的光学响应。讨论了所得涂层光学响应出现的动力学。生产的简易性、图像出现的速度以及创建高分辨率图案的能力，决定了所提出的系统作为湿度传感器或防伪涂层的潜在应用。
