College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
J Mater Chem B. 2019 Mar 14;7(10):1734-1740. doi: 10.1039/c8tb02585a. Epub 2018 Nov 28.
The development of an easy synthetic strategy combined with straightforward tailoring of physical properties and functionalities, such that optimal performance can be targeted for various applications, still remains challenging. Previously, we reported the construction of thermo- and water-responsive strong and tough supramolecular hydrogels based on the cooperatively enhancing effect between H-bonding and hydrophobic forces. Recently, the strategy was greatly simplified to a one-pot two-step approach. In this work, by simply changing the chain extenders used in the second step, different kinds of functional units are easily introduced into the hard segments in the main chain of the copolymers to endow the resultant strong and tough supramolecular hydrogels with various stimulus-responsive properties. A dynamic covalent bond (disulphide or imine bond, e.g.-S-S- or -C[double bond, length as m-dash]N-) in the main chain provides the resulting hydrogels with reduction or pH responsive degradation (gel-to-sol transition) on demand behaviors, respectively; the azobenzene unit endows the yielding hydrogels with UV-Vis controlled stiffness; the pyridine group containing supramolecular hydrogel shows metal ion responsive mechanical and fluorescent behavior. These results provide progress toward addressing the challenges of achieving structural and synthetic simplicity married with sophisticated functionalities.
发展一种简便的合成策略,结合对物理性质和功能的直接剪裁,以针对各种应用实现最佳性能,仍然具有挑战性。此前,我们报道了基于氢键和疏水力之间的协同增强效应构建热响应和水响应的强韧超分子水凝胶。最近,该策略大大简化为一锅两步法。在这项工作中,通过简单地改变第二步中使用的链扩展剂,很容易将不同种类的功能单元引入共聚物主链中的硬段中,从而使所得强韧的超分子水凝胶具有各种刺激响应特性。主链中的动态共价键(例如二硫键或亚胺键 -S-S- 或 -C[双键,长度为破折号]-N-)分别赋予所得水凝胶按需的还原或 pH 响应降解(凝胶到溶胶转变)行为;偶氮苯单元赋予生成的水凝胶具有 UV-Vis 控制的刚度;含吡啶基团的超分子水凝胶表现出对金属离子响应的力学和荧光行为。这些结果为解决实现结构和合成简单性与复杂功能相结合的挑战提供了进展。