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Various ethers were used to mediate the polymerizations of 1,3-pentadiene (PD) initiated by AlCl3 and by allyl chloride (AllyCl)/AlCl3. The introduction of the ethers exert considerable effects on polymer yield and molecular weight due to its interaction with the propagating carbocation. The carbocation reactivity is reduced by this interaction which is subject to the ether's nucleophilicity determined by the steric hindrance of groups adjacent to oxygen. The reduction of carbocation reactivity gives rise to a decrease of polymer yield owing to inhibition of propagation but results in an augmentation of molecular weight due to suppression of various side reactions such as terminations. By using suitably nucleophilic ethers such as diphenyl ether, the polymerization can be mediated to give an high molecular weight polymer in high yield. 相似文献
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MIM开关器件的伏安特性研究 总被引:2,自引:0,他引:2
研究了MIM器件的电导机制,详细介绍了新提出的MIM器件的p-n^--n能带模型,同时利用这一能带模型解释并验证了上电极材料的选择,下电极材料掺N以及用溅射Ta2O5膜代替阳极氧化T2O5膜作绝缘层对MIM器件伏安特性曲线对称性的影响。利用p-n^--n能带模型首次提出用在氢气气氛下热处理的阳极氧化Ta2O5膜作MIM器件的绝缘层可以提高器件的I-V特性曲线的对称性这一新实验方法,另外,本文还较为详细地讨论了阳极氧化过程对MIM器件特性的影响,并首次讨论了对阳极氧化Ta2O5膜进行热处理时,退火方式和反应室气压变化对MIM器件I-V特性的影响。 相似文献