Nov 18 2005
Using building blocks that make up ordinary plastics, but putting them together in a whole new way,University of Michigan研究人员创建了一类轻质，刚性的聚合物，他们预测将对储存氢燃料有用。
The work is described in the current issue of the journal欧洲杯线上买球.
制作新材料（称为共价有机框架（COF））的诀窍是哄骗它们欧洲杯足球竞彩假设可预测的晶体结构 - - 刚性塑料从未做过的事情。
"Normally, rigid plastics are synthesized by rapid reactions that randomly cross-link polymers," said postdoctoral fellow Adrien Côté, who is first author on the Science paper. "Just as in anything you might do, if you do it really fast, it can get disorganized." For that reason, the exact internal structures of such materials are poorly understood, making it difficult to predict their properties. But Côté and colleagues tweaked reaction conditions to slow down the process, allowing the materials to crystallize in an organized fashion instead of assembling helter skelter.
结果，研究人员可以使用X射线晶体学来确定他们创建的每种COF的结构，并使用该信息快速评估其属性。
"Once we know the structure and properties, our methodology allows us to go back and modify the COF, making it perform better or tailoring it for different applications," said Côté.
Côté collaborated on the work with Omar Yaghi, who is the Robert W. Parry Collegiate Professor of Chemistry at U-M. Over the past 15 years, Yaghi has taken a similar approach to producing materials called metal-organic frameworks (MOFs). On the molecular level, MOFs are scaffolds made up of metal hubs linked together with struts of organic compounds. By carefully choosing and modifying the chemical components used as hubs and struts, Yaghi and his team have been able to define the angles at which they connect and design materials with the properties they want.
像MOF一样，可以使COF高度多孔以提高其存储容量。但是与MOF不同，COF不含金属。取而代之的是，它们是由氢，硼，碳，氮和氧气组成的，它们彼此形成牢固的联系（共价键）。
"Using light elements allows you to generate lightweight materials," said Côté. "That's very important for hydrogen fuel storage, because the lighter the material, the more economical it is to transport around in a vehicle. The strong covalent bonds also make COFs very robust materials." Although the main thrust of the current research is creating materials for gas storage in fuel cells, Côté, Yaghi and colleagues also are exploring variations of COFs that might be suitable for use in electronic devices or catalytic applications.
科特说：“这是我们认为将成为一类非常有用的材料的第一步。”欧洲杯足球竞彩
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