13C Nuclear magnetic resonance spectroscopic study of plasticization in solid polymer electrolytes

Preliminary results are presented on the correlation between enhanced solvent mobility and ionic conductivity in plasticized polyether–urethane solid polymer electrolytes using ¹³C nuclear magnetic resonance spectroscopic spin–lattice relaxation time measurements to probe polymer mobility.

Structural characterization of conducting polypyrrole using 13C cross-polarization/magic-angle spinning solid-state nuclear magnetic resonance spectroscopy

¹³C nuclear magnetic resonance (n.m.r.) has been used to study polypyrrole and N-substituted polypyrrole in the solid state. The extent of oxidation appears to be counterion-dependent; in particular, the quinoid structure appears favoured in the films prepared with dodecyl sulfate. Resonances associated with the quinoid unit are lost upon reduction of the polypyrrole film, which supports the idea that the quinoid structure is associated with the oxidized form of polypyrrole. N-substituted polypyrroles have a more distinct resonance at 110 ppm, which is linked to lower degrees of oxidation or charge delocalization in these systems. The decrease in conductivity of polypyrrole upon thermal ageing in air is associated with both the loss of counterion (‘thermal dedoping’) and the decomposition of the quinoid structure in the polymer backbone. There is no indication of carbonyl formation in the solid-state n.m.r. spectra obtained in the present study.

A nuclear magnetic resonance study of 7Li dynamics in polyether-urethane based solid polymer electrolytes

Nuclear magnetic resonance (NMR) is a technique that allows the probing of the dynamics of specific magnetically active nuclei. In the present study a polyethylene glycol network containing varying concentrations of LiClO₄ have been studied using ⁷Li NMR relaxation techniques. A plasticiser, tetraglyme, has been added to several samples to improve the mobility of the polymer and thus of the ionic species. The effects of tetraglyme and salt concentration on the cationic mobility and environment have been investigated using T₁ and T₂ relaxation experiments, with the presence of two cationic species of differing relaxation times (and possibly mobility) reported. The results are discussed with relevance to conductivity measurements made on similar samples.

Carrying weapons and intent to harm among Victorian secondary school students in 1999 and 2009

Objective: 

US policy toward rogue states: Comparing the Bush administration's policy toward Iraq and North Korea

The George W. Bush administration resorted to war to respond to the threat of weapons of mass destruction in Iraq, whereas it virtually ruled out the use of force to resolve the North Korean nuclear issue. By utilizing various strands of realist international relations theories, we trace motivations behind the administration's divergent foreign-policy choices toward rogue states. That the United States rushed to war against Iraq while procrastinating on North Korea presents a puzzle to conventional realism, which postulates that great powers observe changes in relative capabilities and respond accordingly. We argue that policy differences should be embedded in discussion of the administration's foreign-policy grand strategy, which sought to sustain the hegemonic status of the United States in the world. Iraq and North Korea had different implications for Bush's grand strategy, thereby calling for different approaches. By tracing the strategic design of the Bush administration, we attempt to provide a more complete account of policy differences toward rogue states, as well as indicate the significant changes in US policy during the George W. Bush administration and since.