聚儿茶酚胺增强光敏染料在纺织材料上的光致变色和染色性能的研究

Photochromic dyes possess excellent UV-visible light absorption ability and have been widely applied in many fields including medical phototherapy, energy storage, information materials, anti-counterfeiting and textile materials. However, it is found that photochromic dyes have very low adsorption and uptake on materials surfaces due to their non-planar molecular structures. Because photochromic dyes expose to UV radiations whose energy is much higher than that needed for their structural transformation, their photochromic fatigue resistance will gradually be decreased and even completely disappeared. In nature, once mussels contact with a substrate, they can secret liquid adhesives which contain high contents of polymeric catechol amines and can harden within a few seconds to obtain permanent adhesion ability through many interactions including hydrogen bonds, ionic bonds, covalent bonds, etc. Inspired by this phenomenon, for the purpose to enhance dye adsorption and uptake of photochromic dyes, this project is proposed to utilize in-situ-formed polymeric catechol amines as dyeing anchors to fix dye molecules on textile materials. Furthermore, there are rich functional groups of hydroxyl, amino and indolyl in the chemical structures of polymeric catechol amines. They can exhaust excessive UV radiations through many interactions, such as inter- or intramolecular hydrogen bonds, to improve the photochromic fatigue resistance and light fastness of the dyed textile materials. From the preliminary study results, the proposed biomimetic approach shows the high feasibility on textile materials.

光敏染料具有优异的紫外可见光吸收能力，在医学光疗、储能、信息材料、防伪、纺织材料等众多领域有着广泛的应用。但是，在应用过程中发现光敏染料的分子平面性较差导致在材料表面的吸附负载较低。由于受到过量的紫外线辐射，在应用中光敏染料的光致变色耐疲劳性逐渐降低，甚至完全失去光致变色的能力。在自然界中，贝类生物与物体表面接触后会立即分泌出含有高含量聚儿茶酚胺的粘液，通过其形成的氢键、离子键、共价键等多种相互作用在数秒内固化形成持久的粘附能力。受此启发，本课题利用室温条件下原位自聚合形成的聚儿茶酚胺的粘附能力将光敏染料固着在纺织材料上，以提高光敏染料的上染性能。而且，在聚儿茶酚胺的化学结构中丰富的羟基、氨基、吲哚基等官能团能够通过分子内或分子间氢键等多种相互作用将过量的紫外线辐射消耗掉，从而提高染色后纺织材料的光致变色耐疲劳性和光牢度性能。前期研究结果表明本课题具有很高的可行性。

光敏染料普遍有与纺织纤维亲和力较差问题, 在染色过程中常常依赖于纤维的种类，缺乏应用的通用性和普遍性。另一方面，由于受到过量的紫外线辐射，光敏染料的光致变色耐疲劳性逐渐降低，甚至完全失去光致变色的能力。加入紫外线吸收剂方法，不仅不能从根本上提高光敏染料的耐疲劳性，还会因为部分紫外线被紫外线吸收剂吸收后致使光敏染料受到的紫外线辐射量减少，从而影响染色织物的光致变色性能。本项目成功验证了聚儿茶酚胺对染料的负载能力。将聚儿茶酚胺与光敏染料在温和条件下协同作用于纺织材料，基本实现了对不同织物的着色，突破了对染色纤维种类的限制。与此同时，通过多巴胺和光敏染色分子的化学键合，发展了对染色底物无依赖性的，新型的含双儿茶酚的偶氮光敏染料。染色织物的色泽和鲜艳度得到改善的同时也实现了UV 防护性能的提升。此外，通过静电纺制备的同时参杂了聚儿茶酚胺颗粒和光敏染料的纳米纤维垫在光致变色过程中不仅能维持良好的灵敏性与变色回复性，而且光致变色的耐疲劳性也得到了明显提高。与添加传统的紫外线吸收助剂相比，聚儿茶酚胺颗粒与光敏染料的直接负载，缩短了织物的处理步骤，同时减少了对环境的污染，更重要的是，聚儿茶酚胺为人体色素的仿生物，其处理织物的功能性和安全性更高。这具有积极的科学意义和社会价值。