基于温度开关的光响应智能水凝胶用于可逆信息加密和解密

Temperature-switch-based light-responsive smart hydrogel for reversible message encryption and decryption

在智能凝胶防伪系统中使用的光、热、电、pH等刺激响应性水凝胶,是一种有前途的信息加密和解密材料.然而单一刺激会限制高水平的防伪.因此,需要协同使用多种刺激来提升信息安全等级.本研究设计了一种高透明度的海藻酸钠-聚丙烯酰胺(SA-PAM)水凝胶作为基体,利用无机变色材料钼酸铵(Mo7)赋予其凝胶光致变色特性.此外,温敏材料聚N-异丙基丙烯酰胺(PNIPAM)可使凝胶在最低临界相变温度(LCST)下发生体积相变,进而改变凝胶的宏观状态,可以通过调整凝胶体系中亲水单体和疏水单体的比例来控制LCST.利用紫外线(UV)作为“墨水”输入信息,以温度作为“开关”来加密/解密信息.总之,该水凝胶具有出色的光致变色能力,可在10 s内着色,紫外光吸收率最高可达96.23%.利用水凝胶对光-热刺激展现出的非凡响应能力,可以实现其迅速显示和隐藏信息的功能,从而确保信息安全,这为光致变色水凝胶在信息加密领域的应用提供了一种新方法.

The use of stimulus-responsive hydrogels in intelligent gel anti-counterfeiting systems is a promising method to encrypt and decrypt information.External stimuli such as light,heat,electricity,magnetism and pH can alter the output information,while a single stimulus will limit higher levels of anti-counterfeiting.Therefore,multiple stimuli should be synergistically used to enhance information security.In this study,a highly transparent sodium alginate-polyacrylamide(SA-PAM)hydrogel is designed as the matrix.An inorganic color-changing material,ammonium molybdate(Mo7),is used to impart the gel with photochromic characteristics.Furthermore,poly-N-isopropylacrylamide(PNIPAM),a temperature-sensitive material,makes the gel undergo a bulk phase transition at the lowest critical phase transition temperature(LCST),which in turn alters macroscopic state of the gel.The LCST can also be controlled by adjusting the ratio of hydrophilic and hydrophobic monomers in the gel system.By using ultraviolet(UV)light as the“ink”,the information is input,and temperature is used as the“switch”to encrypt/decrypt the information.Overall,the hydrogel exhibits excellent photochromic ability and can be colored within 10 s,while exhibiting a maximum UV light absorption rate of 96.23%.The hydrogel can rapidly reveal or conceal the information based on the response of the hydrogel to light and heat stimuli,thus ensuring that the information remains secure.This paper presents a novel approach of utilizing photochromic hydrogels in the field of information encryption.