《专业英语3.three_howcanplasticbecomeconductive》由会员分享，可在线阅读，更多相关《专业英语3.three_howcanplasticbecomeconductive（40页珍藏版）》请在金锄头文库上搜索。
1、How can plastic become conductive?塑料为什么导电？1We are used to the great impact scientific discoveries have on our ways of thinking. The 2000 years Nobel Prize in Chemistry is no exception. What we have been taught about plastic is that it is a good insulator - otherwise we should not use it as insulatio
2、n in electric wires. The Nobel Prize in Chemistry, 20002But now the time has come when we have to change our views. Plastic can indeed, under certain circumstances, be made to behave very like a metal - a discovery for which Alan J. Heeger, Alan G. MacDiarmid and Hideki Shirakawa(白川英树) had received
3、the Nobel Prize in Chemistry 2000.The Nobel Prize in Chemistry, 2000艾伦-J-黑格 艾伦-G-马克迪尔米德白川英树3Plastics are polymers, molecules that form long chains, repeating themselves like pearls(珍珠) in a necklace. In becoming electrically conductive, a polymer has to imitate a metal, that is, its electrons need t
4、o be free to move and not bound to the atoms. How can plastic become conductive?4The first condition for this is that the polymer consists of alternating single and double bonds(交替 的单双键), called conjugated double bonds(共轭双键 ). Polyacetylene(聚乙炔), prepared through polymerization of the hydrocarbon ac
5、etylene (乙炔), has such a structure:How can plastic become conductive?共轭双键: 有机化合物的一种结构形式 。其特征是两个双键为一个单键所间隔.5However, it is not enough to have conjugated double bonds. To become electrically conductive, the plastic has to be disturbed - either by removing electrons from (oxidation氧化), or inserting the
6、m into (reduction 还原), the material. The process is known as doping(掺杂).How can plastic become conductive?又，高分子聚合物的导电性导电聚合物是一种具 共轭结构拥有聚乙炔。当称导电塑胶与导电塑料 ，可移走电子生成空穴，或添掺杂后经过，双键 在分子链上自由移动，从空穴加电子，使电子或 聚乙炔、而形成导电分子。常见的导电聚合物有 ，以及聚苯胺、聚吡咯、聚噻吩和聚对苯乙烯撑 . 它们的衍生物6The game in the illustration offers a simple model of
7、 a doped polymer. The pieces cannot move unless there is at least one empty “hole“. In the polymer each piece is an electron that jumps to a hole vacated(腾出) by another one. This creates a movement along the molecule - an electric current.How can plastic become conductive?This model is greatly over-
8、 simplified, and we shall consider a more “chemical“ model later.7How can plastic become conductive?What Heeger, MacDiarmid and Shirakawa found was that a thin film of polyacetylene(聚乙炔) could be oxidised(氧化) with iodine vapour(碘蒸汽), increasing its electrical conductivity a billion times. 8How can p
9、lastic become conductive?This sensational(引起轰动的) finding was the result of their impressive work, but also of coincidences(巧 合) and accidental circumstances(偶然情况). Let us, shortly, tell the story of one of the great chemical discoveries of our time.9How polymer conductivity was revealed - and the im
10、portance of a coffee-breakThe leading actor in this story is the hydrocarbon(碳 氢化合物) polyacetylene, a flat molecule with an angle of 120 between the bonds and hence existing in two different forms, the isomers(异构物) cis- polyacetylene(顺式聚乙炔)and trans-polyacetylene ( 反式聚乙炔). 10How polymer conductivity
11、 was revealed - and the importance of a coffee-breakAt the beginning of the 1970s, the Japanese chemist Shirakawa found that it was possible to synthesize polyacetylene in a new way, in which he could control the proportions of cis- and trans-isomers in the black polyacetylene film that appeared on
12、the inside of the reaction vessel(反应容器). Once - by mistake - a thousand-fold too much catalyst(催化剂) was added. To Shirakawas surprise, this time a beautiful silvery film appeared.于实验室制韩国边衡直博士进修的东京工业大学在日本年1967 黑色，使得本来该得到催化剂作聚乙炔时，加入超量的一千倍 银白色的薄膜（反式聚却变成了粉末聚乙炔（顺式聚乙炔）， 即据此结果开始博士白川英树助理的池田研究所时任乙炔）。. 研究聚乙炔1
13、1How polymer conductivity was revealed - and the importance of a coffee-breakShirakawa was stimulated by this discovery. The silvery film was trans-polyacetylene, and the corresponding reaction at another temperature gave a copper-coloured film instead. The latter film appeared to consist of almost
14、pure cis-polyacetylene. This way of varying temperature and concentration of catalyst was to become decisive for the development ahead.12How polymer conductivity was revealed - and the importance of a coffee-breakIn another part of the world, chemist MacDiarmid and physisist Heeger were experimentin
15、g with a metallic-looking film of the inorganic polymer(无机 聚合物) sulphur nitride, (SN)x. MacDiarmid referred to this at a seminar(研讨会) in Tokyo. Here the story could have come to a sudden end, had not Shirakawa and MacDiarmid happened to meet, accidentally, during a coffee-break.13How polymer conduct
16、ivity was revealed - and the importance of a coffee-breakWhen MacDiarmid heard about Shirakawas discovery of an organic polymer that also gleamed like silver, he invited Shirakawa to the University of Pennsylvania(宾 夕法尼亚) in Philadelphia(费城). They set about modifying polyacetylene by oxidation with iodine vapour. 14How polymer conductivity was revealed - and the importance of a coffee-breakShirakawa knew that the optical pr
