Microstructural study of a nitroxide-mediated poly(ethylene oxide)/polystyrene block copolymer (PEO-<i>b</i>-PS) by electrospray tandem mass spectrometry

Girod, Marion; Phan, Trang N. T.; Charles, Laurence

doi:10.1016/j.jasms.2008.04.030

Cited by 42 publications

(60 citation statements)

References 56 publications

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“…(COOH) radical from the substituent linking the PEO and PS blocks to generate series b n 00 -87 (Girod, Phan, & Charles, 2008a). Note that fragmentation at the PEO block does not occur, consistent with a higher energy requirement for this process than the competitive C-ON bond cleavage at the end of the PS block.…”

Section: B Linear Polystyrenes With Labile Chain Endsmentioning

confidence: 81%

“…* A combination of 1,5-and 1,3-H transfers is needed for this isomerization. The fragments requiring 1,3-H transfers (b 1 00 -87 and b 3 00 -87) are not observed from the corresponding silverated oligomer (which otherwise gives a very similar fragmentation pattern), because of high energy requirements (Girod et al, 2008a). Reprinted (in part) from J Am Soc Mass Spectrom, 19, Girod M, Phan TNT, Charles L., Microstructural study of a nitroxidemediated poly(ethylene oxide)/polystyrene block copolymer (PEO-b-PS) by electrospray tandem mass spectrometry, 1163-1175, Copyright 2008a, with permission from Elsevier.…”

Section: Poly(a A-methylstyrene) and Phenyl-substituted Polystyrenesmentioning

confidence: 99%

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Fragmentation pathways of polymer ions

Wesdemiotis

Solak

Polce

et al. 2011

Mass Spectrometry Reviews

178

290

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Tandem mass spectrometry (MS/MS) is increasingly applied to synthetic polymers to characterize chain-end or in-chain substituents, distinguish isobaric and isomeric species, and determine macromolecular connectivities and architectures. For confident structural assignments, the fragmentation mechanisms of polymer ions must be understood, as they provide guidelines on how to deduce the desired information from the fragments observed in MS/MS spectra. This article reviews the fragmentation pathways of synthetic polymer ions that have been energized to decompose via collisionally activated dissociation (CAD), the most widely used activation method in polymer analysis. The compounds discussed encompass polystyrenes, poly(2-vinyl pyridine), polyacrylates, poly(vinyl acetate), aliphatic polyester copolymers, polyethers, and poly(dimethylsiloxane). For a number of these polymers, several substitution patterns and architectures are considered, and questions regarding the ionization agent and internal energy of the dissociating precursor ions are also addressed. Competing and consecutive dissociations are evaluated in terms of the structural insight they provide about the macromolecular structure. The fragmentation pathways of the diverse array of polymer ions examined fall into three categories, viz. (1) charge-directed fragmentations, (2) charge-remote rearrangements, and (3) charge-remote fragmentations via radical intermediates. Charge-remote processes predominate. Depending on the ionizing agent and the functional groups in the polymer, the incipient fragments arising by pathways (1)-(3) may form ion-molecule complexes that survive long enough to permit inter-fragment hydrogen atom, proton, or hydride transfers.

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Section: B Linear Polystyrenes With Labile Chain Endsmentioning

confidence: 81%

Section: Poly(a A-methylstyrene) and Phenyl-substituted Polystyrenesmentioning

confidence: 99%

Fragmentation pathways of polymer ions

Wesdemiotis

Solak

Polce

et al. 2011

Mass Spectrometry Reviews

178

290

View full text Add to dashboard Cite

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“…Lithium turns out to al. (245) showed that lithium enhanced the lymphocyte response to phytohemagglutinin (101) in leukemia pabe a potent stimulant of bone marrow stem cells. For example, it is used after chemotherapy, radiation thertients.…”

Section: Lithium-induced Granulocytosismentioning

confidence: 99%

Review of Lithium Effects on Brain and Blood

2009

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Clinicians have long used lithium to treat manic depression. They have also observed that lithium causes granulocytosis and lymphopenia while it enhances immunological activities of monocytes and lymphocytes. In fact, clinicians have long used lithium to treat granulocytopenia resulting from radiation and chemotherapy, to boost immunoglobulins after vaccination, and to enhance natural killer activity. Recent studies revealed a mechanism that ties together these disparate effects of lithium. Lithium acts through multiple pathways to inhibit glycogen synthetase kinase-3β (GSK3β). This enzyme phosphorylates and inhibits nuclear factors that turn on cell growth and protection programs, including the nuclear factor of activated T cells (NFAT) and WNT/β-catenin. In animals, lithium upregulates neurotrophins, including brain-derived neurotrophic factor (BDNF), nerve growth factor, neurotrophin-3 (NT3), as well as receptors to these growth factors in brain. Lithium also stimulates proliferation of stem cells, including bone marrow and neural stem cells in the subventricular zone, striatum, and forebrain. The stimulation of endogenous neural stem cells may explain why lithium increases brain cell density and volume in patients with bipolar disorders. Lithium also increases brain concentrations of the neuronal markers n-acetyl-aspartate and myoinositol. Lithium also remarkably protects neurons against glutamate, seizures, and apoptosis due to a wide variety of neurotoxins. The effective dose range for lithium is 0.6-1.0 mM in serum and >1.5 mM may be toxic. Serum lithium levels of 1.5-2.0 mM may have mild and reversible toxic effects on kidney, liver, heart, and glands. Serum levels of >2 mM may be associated with neurological symptoms, including cerebellar dysfunction. Prolonged lithium intoxication >2 mM can cause permanent brain damage. Lithium has low mutagenic and carcinogenic risk. Lithium is still the most effective therapy for depression. It "cures" a third of the patients with manic depression, improves the lives of about a third, and is ineffective in about a third. Recent studies suggest that some anticonvulsants (i.e., valproate, carbamapazine, and lamotrigene) may be useful in patients that do not respond to lithium. Lithium has been reported to be beneficial in animal models of brain injury, stroke, Alzheimer's, Huntington's, and Parkinson's diseases, amyotrophic lateral sclerosis (ALS), spinal cord injury, and other conditions. Clinical trials assessing the effects of lithium are under way. A recent clinical trial suggests that lithium stops the progression of ALS.

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“…Unique properties in selective solvents can be obtained with amphiphilic copolymers, consisting of both hydrophilic and hydrophobic blocks (Girod et al 2008). When the environmental conditions (temperature, pH, ionic strength) change, the copolymers self-assemble into micelles, vesicles and/or other supramolecular structures (Gil and Hudson 2004).…”

Section: Introductionmentioning

confidence: 99%

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

Koleva

et al. 2013

ACT

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The influence of limited concentration, of 0.025 wt.% per cement weight, poly (ethylene oxide) -block -polystyrene vesicles on the hydration process, microstructure and micromechanical properties of cement paste at early hydration age of maximum 7 days are discussed. Isothermal calorimetry and non-evaporable water content tests indicate that the admixed vesicles have no apparent influence on the process of cement hydration, but affect microstructural properties. Whereas nitrogen adsorption tests reveal that the gel pore structure of the vesicles-modified matrix is almost identical to the vesicles-free one, mercury intrusion porosimetry proves refined capillary porosity and reduced total porosity in the presence of admixed vesicles. Nano-indentation supports the above observations and indicates that the admixed vesicles act as nucleation sites, leading to a more uniform distribution of low density hydration products.

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Microstructural study of a nitroxide-mediated poly(ethylene oxide)/polystyrene block copolymer (PEO-b-PS) by electrospray tandem mass spectrometry

Cited by 42 publications

References 56 publications

Fragmentation pathways of polymer ions

Fragmentation pathways of polymer ions

Review of Lithium Effects on Brain and Blood

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

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