Solubility of carbon nanotubes

2000 ◽  
Vol 633 ◽  
Author(s):  
Marc In Het Panhuis ◽  
Jonathan N. Coleman ◽  
Werner J. Blau
Keyword(s):  
Carbon Nanotubes ◽  
Electron Paramagnetic Resonance ◽  
Experimental Evidence ◽  
Experimental Technique ◽  
Carbon Material ◽  
Conjugated Polymer ◽  
Paramagnetic Resonance ◽  
Sample Bottle ◽  
Carbon Soot ◽  
Electron Paramagnetic

AbstractWe have described a novel experimental technique to separate nanotubes from other unwanted carbon species in arc generated carbon soot. A conjugated polymer was used to bind to nanotubes in solution. The resultant hybrid was soluble while extraneous carbon material formed a sediment at the bottom of the sample bottle. This process was monitored using electron paramagnetic resonance (EPR) which showed that 63% of nanotubes were kept in solution while 98.1% of impurities were rejected. Optimal polymer characteristics for nanotube solubility were identified using geometry optimisation and experimental evidence. It was calculated that a successful polymer has a flat shaped helical backbone with solvent solubilising groups projected outwards. This is achieved with the following polymer characteristics, two solvent solubilising groups on a twist allowing π-conjugated backbone.

Purity and Solubility of Nanotubes in Arc Discharge Carbon Powder

2000 ◽  
Vol 633 ◽  
Author(s):  
Jonathan N. Coleman ◽  
Alan B. Dalton ◽  
Brendan McCarthy ◽  
Robert C. Barklie ◽  
Werner J. Blau
Keyword(s):  
Electron Microscopy ◽  
Electron Paramagnetic Resonance ◽  
Carbon Material ◽  
Conjugated Polymer ◽  
Arc Discharge ◽  
Carbon Powder ◽  
Paramagnetic Resonance ◽  
Sample Bottle ◽  
Carbon Soot ◽  
Electron Paramagnetic

AbstractWe have described a novel experimental technique to separate nanotubes from other unwanted carbon species in arc generated carbon soot. A conjugated polymer was used to bind to nanotubes in solution. The resultant hybrid was soluble while extraneous carbon material formed a sediment at the bottom of the sample bottle. This process was monitored using electron paramagnetic resonance (EPR) which showed that 63% of nanotubes were kept in solution while 98.1% of impurities were rejected. This allowed the calculation of the nanotube content in the carbon soot using EPR and thermo-gravitational analysis (TGA) yielding a purity value of 34% for the soot used in this study. This is compatible with estimates made using electron microscopy.

scholarly journals First experimental evidence for a bis-ethene chromium(I) complex forming from an activated ethene oligomerization catalyst

2020 ◽  
Vol 6 (51) ◽  
pp. eabd7057
Author(s):  
S. Chabbra ◽  
D. M. Smith ◽  
N. L. Bell ◽  
A. J. B. Watson ◽  
M. Bühl ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Experimental Evidence ◽  
Catalytic System ◽  
Isotope Labeling ◽  
Catalytic Transformation ◽  
Mechanistic Studies ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

A bis-ethene chromium(I) species, which is the postulated key intermediate in the widely accepted metallacyclic mechanism for ethene oligomerization, is experimentally observed. This catalytic transformation is an important commercial route to linear α-olefins (primarily, 1-hexene and 1-octene), which act as comonomers for the production of polyethene. Here, electron paramagnetic resonance studies of a catalytic system based on [Cr(CO)4(PNP)][Al(OC(CF3)3)4] [PNP = Ph2PN(iPr)PPh2] activated with Et6Al2 provide the first unequivocal evidence for a chromium(I) bis-ethene complex. The concentration of this species is enhanced under ethene and isotope labeling studies that confirm its composition as containing [Cr(C2H4)2(CO)2(PNP)]+. These observations open a new route to mechanistic studies of selective ethene oligomerization.

Applications of EPR Spectrometer in Environmental Samples

2015 ◽  
Vol 1092-1093 ◽  
pp. 589-592
Author(s):  
Shao Hua Liao ◽  
Fang Yang ◽  
Fang Fang Li ◽  
Jing Yang ◽  
Min Wu
Keyword(s):  
Carbon Nanotubes ◽  
Electron Paramagnetic Resonance ◽  
Free Radicals ◽  
Transition Metals ◽  
Environmental Samples ◽  
High Sensitivity ◽  
Organic Radicals ◽  
Paramagnetic Resonance ◽  
Potential Risks ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) spectrometer was widely applied to physics, chemistry and biomedicine. This research provided possible electron and valence information of environmental samples interaction through high sensitivity. The EPR signals of transition metals and organic radicals were distinguished well. Three kinds of carbon nanotubes (CNTs) (MW50, MW30 and MWG) had strong EPR signals. Addition of transition metals may be a suitable way to decrease environmentally persistent free radicals (EPFRs). The potential risks of EPFRs in BC and the reactive free electron in transition metals must be addressed to ensure their safe and scientific absorption application.

Electron paramagnetic resonance study of non-exchangeable vanadium(IV) in rectorites

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 283-287 ◽  
Author(s):  
B. A. Goodman ◽  
P. H. Nadeau
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Experimental Evidence ◽  
Epr Spectroscopy ◽  
Electron Paramagnetic Resonance Study ◽  
Paramagnetic Resonance ◽  
Octahedral Sites ◽  
Two Samples ◽  
Electron Paramagnetic

AbstractEPR spectroscopy was used to provide evidence for the existence of vanadium(IV) in two samples of rectorite. Possible sites for the vanadium are the tetrahedral and octahedral sites in the 2:1 layers and the non-exchangeable interlayer sites in the paragonite part of the structure. Consideration is given to each of these possibilities but the experimental evidence is insufficient to identify conclusively the location of the vanadium. Since substantial amounts of vanadium(IV) were present in the only well-defined rectorite samples obtainable, it is possible that the formation of rectorite is facilitated by the presence of vanadium.

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