Nanometer structure and conductor mechanism of polymer modified by metal ion implantation
摘要:
Polyethylene terephthalate (PET) has been modified by Ag, Ti, Cu and Si ion implantation with a dose ranging from I X 10(16) to 2 x 10(17) ions/cm(2) using a metal vapor vacuum arc (MEVVA) source. The electrical properties of PET have been improved by metal ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. The results show that the conductive behavior of a metal ion implanted sample is different from Si-implantation samples. In order to understant the mechanism of electrical conduction, the structures of implanted layer were observed in detail by XRD and TEM. The nano carbon particles were dispersed in implanted PET. The nano metallic particles were built up in metallic ion implanted layers with dose range from 1 x 10(16) to 1 x 10(17) ions/cm(2). The nanometer metal net structure was formed in implanted layer when a dose of 2 x 10(17) ions/cm(2) is reached. Anomalous fractal growths were observed. These surface structure changes revealed conducting mechanism evolution. It is believed that the change would result in an improvement of the conductive properties. The conducting mechanism will be changed with increasing metal ion dose.
The regioselectivity of nitrone and nitrile oxide cycloadditions to alkylidenecyclopropanes
作者:Alberto Brandi、Franca M. Cordero、Francesco De Sarlo、Remo Gandolfi、Andrea Rastelli、Marisa Bagatti
DOI:10.1016/0040-4020(92)85008-3
日期:1992.1
The 1,3-dipolarcycloaddition of nitrile oxides and a nitrone to alkylidencyclopropanes 1–5,used as model for methylenecyclopropanes substituted with arylgroup (1), electron-releasing groups (2 and 3) and electron-attracting groups (4 and 5) is reported. The cycloaddition to alkylidenecyclopropanes 1–3 gives prevalently or exclusively adducts bearing the cyclopropane ring on the C4 position of the
Regioselectivity in the 1,3-dipolar cycloaddition of nitrile oxides to alkylidenecyclopropanes.
作者:Alberto Brandi、Silvio Carli、Antonio Guarna、Francesco De Sarlo
DOI:10.1016/s0040-4039(00)96402-5
日期:1987.1
The 1,3-dipolarcycloaddition of nitrileoxides to methylenecyclopropanes substituted on the exocyclic double bond gives prevalently or exclusively 4-spirocyclopropane isoxazolines when the substituent is arylic or alkylic group, 5-spirocyclopropane isoxazolines when the substituent is an electron-withdrawing group. Adducts 16 and 17 selectively rearrange photochemically to the enaminoenone 19.
Stereochemistry of the methylenecyclopropane rearrangement
作者:W. von E. Doering、H.D. Roth
DOI:10.1016/s0040-4020(01)92859-5
日期:1970.1
3-dicarboxylate and its two products of thermal rearrangement, methyl syn- and anti-2-carbomethoxycyclopropylideneacetate, has allowed the exclusion of a planar transition state and the construction of a unique mechanism in which the substituents at a pivotal atom remain perpendicular to the plane of the system of four atoms that constitute the methylenecyclopropane of starting material and product.