Researchers have synthesized a material with a distinctive structure involving woven organic polymers that provide it with special elastic properties. Covalent organic frameworks (COFs) are structures created with organic building blocks that link together. They are appealing because their low density and high porosity has many promising applications, such as for storing gas or for optoelectronics, but previously, synthesized COFs have been too rigid. Creating more flexible COFs, those that resemble woven fabrics, has been challenging on a molecular level. The synthesis method developed by Yuzhong Liu et al. could lead to a new field of material science. First, the authors created a copper-based framework. They added organic compounds that "link" together, interlacing 1D units to make 2D and 3D structures. Each of the threads making up the framework is a helix, and the helices are covalently linked at "points of registry." These points allow the threads many degrees of flexibility without collapsing the overall structure. Upon removal of the copper ions, the structure remains intact. The threads are able to slide against each other, increasing the elasticity of the material tenfold. Adding copper solution results in complete restoration of the original material. A Perspective by Enrique Gutierrez-Puebla provides more context about this new woven material and its potential applications.
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Journal
Science