Hydrogels with oriented structures exhibit birefringence and display different interference colors between crossed polarizers, which has attracted increasing attention in the fields of information encryption. However, it remains a challenge to introduce complex anisotropic microstructures into hydrogels and enabling them to display high-resolution interference patterns with erasable and rewritable properties. In this study, we report a uniaxially oriented anisotropic polyvinyl alcohol (PVA) hydrogel mediated by dynamic borate ester bonds. Different high-resolution interference patterns can be written or transfer-printed quickly by disrupting the localized PVA-B(OH)4−complex structures with HCl solution. The reversible formation and dissociation of the PVA-B(OH)4− complex structures allow the interference pattern to be repeatedly erased and rewritten. The excellent stability of the crystalline domains of PVA confers the ability for reversible transformation between hydrogel and dry film states without compromising the accuracy and reliability of the pattern information. The created dry film with a fingerprint pattern can be used to assemble an unforgeable card, which can instantly display a fingerprint pattern in front of a cell phone screen. Double encryption of the patterned information was achieved by drying the patterned hydrogel into a curly shape and utilizing its three-dimensional structure to increase the security of the information.

中文翻译：

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用于信息加密的动态硼酸酯键介导的图案化各向异性水凝胶


具有定向结构的水凝胶表现出双折射，并在交叉偏振片之间表现出不同的干涉颜色，这在信息加密领域引起了越来越多的关注。然而，将复杂的各向异性微结构引入水凝胶中，并使它们能够显示具有可擦除和可重写特性的高分辨率干涉图案仍然是一个挑战。在这项研究中，我们报道了一种由动态硼酸酯键介导的单轴取向各向异性聚乙烯醇 （PVA） 水凝胶。通过使用 HCl 溶液破坏局部 PVA-B（OH）4− 复合结构，可以快速写入或转移打印不同的高分辨率干涉图。PVA-B（OH）4− 复合物结构的可逆形成和解离允许干涉图案被反复擦除和重写。PVA 结晶域的出色稳定性赋予了在水凝胶和干膜状态之间发生可逆转变的能力，而不会影响图案信息的准确性和可靠性。带有指纹图案的制作干膜可用于组装一张不伪造的卡片，它可以立即在手机屏幕前显示指纹图案。通过将图案化的水凝胶干燥成卷曲的形状并利用其三维结构来提高信息的安全性，实现了图案化信息的双重加密。