14296-16-3Relevant articles and documents
Decreasing the alkyl branch frequency in precision polyethylene: Effect of alkyl branch size on nanoscale morphology
Inci, Bora,Lieberwirth, Ingo,Steffen, Werner,Mezger, Markus,Graf, Robert,Landfester, Katharina,Wagener, Kenneth B.
, p. 3367 - 3376 (2012)
Synthesis and morphological characterization are reported for a series of 13 precision branched polyethylene structures, the branch being placed on every 39th carbon and varying in size from methyl to pentadecyl group. A recently established synthetic scheme for preparation of the symmetrical α,ω-diene monomer was employed to increase the number of methylene carbons between the branch points from 20 to 38, yielding polymers with 5.26 mol % α-olefin incorporation. The morphology of these polymers was investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). Methyl branching significantly reduces the melting point and single crystal lamellae thickness of unbranched polyethylene. On the other hand, all further branches from ethyl to pentadecyl produce polymers that have similar melting points and single crystal lamellae thicknesses. A clear change in the morphology of both solution and melt-grown crystals of these polymers was observed from a situation where the methyl branch is incorporated in the polymer's unit cell to one where branches of greater mass are mostly expelled from the unit cell.
The Micellar Properties of Ionic Surfactants Consisting of the α,ω-Type Surfactant Ion and the Same Type Counter Ion
Satake, Iwao,Morita, Tadakazu,Maeda, Tamaki,Hayakawa, Katumitu
, p. 761 - 765 (1997)
The micellar properties of N, N, N, N', N', N'-hexamethyl-1, 20-icosanediyldiammonium, or the corresponding di(1-pyridinium)alkanedioates -OOC(CH2)nCOO- (n = 2 - 10), were studied by conductivity and pyrene fluorescence measurements. In both systems, the critical micelle concentration (cmc) varied little up to n = 4, but decreased rapidly with a further increase in n. The binding degree (β) of the alkanedioate counter ion was virtually independent of the type of surfactant ion head group and gradually increased from 0.69 at n = 2 to 0.91 at n= 10. The observed n dependences of cmc and β were similar to those of the conventional ionic surfactants with an α,ω-type counter ion, indicating the importance of the hydrophobic interaction between the hydrocarbon part of the counter ion and the micellar core. On the basis of a phase-separation model, the transfer free energy per methylene group of the counter ion from aqueous-to-micellar environments was estimated to be about - 1.0 RT. The fluorescence measurements suggest that the surface layer of the micelle becomes progressively loose as n decreases. The micelle aggregation numbers of the bis (trimethylammonium) salts are of the order of 50.
Preparation and characterization of crosslinked poly(vinylimidazolium) anion exchange membranes for artificial photosynthesis
Carter, Blaine M.,Keller, Laura,Wessling, Matthias,Miller, Daniel J.
, p. 23818 - 23829 (2019)
The interrelated nature of material properties in ion exchange membranes, such as ion exchange capacity and water uptake, frustrates the systematic study of how membrane chemistry and structure affect the transport of water, ions, and uncharged solutes in the membrane. Herein, we describe the preparation of a series of crosslinked poly(vinylimidazolium) anion exchange membranes by UV-photopolymerization of difunctional (i.e., crosslinking) and monofunctional (i.e., non-crosslinking) monomers, in which the ion exchange capacity and crosslink density may be independently controlled. Ion exchange membranes used in artificial photosynthesis (solar-driven CO2 reduction) devices must permit the transport of electrolyte ions and minimize the crossover of CO2 reduction products (e.g., alcohols) between electrodes. The water content, methanol (CO2 reduction product) permeability, and ionic conductivity of the membranes were evaluated. Ionic conductivity and methanol permeability were increased by reducing crosslink density or increasing solvent content in the prepolymerization solvent mixture. For all prepared membranes, methanol permeability was directly correlated with water volume fraction in the membrane. Minimizing the water volume fraction is critical to the design of membranes with low permeability to CO2 reduction products.
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Woolford,R.G.
, p. 1846 - 1850 (1962)
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Cysteine-Targeted Insecticides against A. gambiae Acetylcholinesterase Are Neither Selective nor Reversible Inhibitors
Gorecki, Lukas,Andrys, Rudolf,Schmidt, Monika,Kucera, Tomas,Psotka, Miroslav,Svobodova, Barbora,Hrabcova, Veronika,Hepnarova, Vendula,Bzonek, Petr,Jun, Daniel,Kuca, Kamil,Korabecny, Jan,Musilek, Kamil
, p. 65 - 71 (2019/12/25)
Acetylcholinesterase cysteine-targeted insecticides against malaria vector Anopheles gambia and other mosquitos have already been introduced. We have applied the olefin metathesis for the preparation of cysteine-targeted insecticides in high yields. The prepared compounds with either a succinimide or maleimide moiety were evaluated on Anopheles gambiae and human acetylcholinesterase with relatively high irreversible inhibition of both enzymes but poor selectivity. The concept of cysteine binding was not proved by several methods, and poor stability was observed of the chosen most potent/selective compounds in a water/buffer environment. Thus, our findings do not support the proposed concept of cysteine-targeted selective insecticides for the prepared series of succinimide or maleimide compounds.
