The kinetics of the polymerization of styrene initiated by n -butyl lithium in hydrocarbon media

1962 ◽  
Vol 268 (1333) ◽  
pp. 260-275 ◽  
Keyword(s):  
Degree Of Polymerization ◽  
Complete Conversion ◽  
Initiator Concentration ◽  
Butyl Lithium ◽  
Initiation And Propagation ◽  
Quantitative Results ◽  
Kinetics Of ◽  
Hydrocarbon Media

The kinetics of the polymerization of styrene initiated by n-butyl lithium in hydrocarbon media has been studied under conditions where both initiation and propagation of growing chains takes place simultaneously and in the absence of a termination reaction. Under the conditions employed, the initiator is incompletely consumed at complete conversion of monomer to polymer and consequently the degree of polymerization of the polystyrene is greater than the ratio of monomer to initiator concentration. The quantitative results support the mechanism previously proposed by Worsfold & By water for this polymerization.

scholarly journals Oriented arrangement of simple monomers enabled by confinement: towards living supramolecular polymerization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingtong Zong ◽  
Si-Min Xu ◽  
Wenying Shi ◽  
Chao Lu
Keyword(s):  
Activation Barrier ◽  
Degree Of Polymerization ◽  
Supramolecular Polymer ◽  
Energy Principle ◽  
Spontaneous Nucleation ◽  
Pyrene Derivatives ◽  
Multifunctional Molecules ◽  
Double Hydroxide ◽  
Supramolecular Polymerization ◽  
Kinetics Of

AbstractThe living supramolecular polymerization technique provides an exciting research avenue. However, in comparison with the thermodynamic spontaneous nucleation, using simple monomers to realize living supramolecular polymerization is hardly possible from an energy principle. This is because the activation barrier of kinetically trapped simple monomer (nucleation step) is insufficiently high to control the kinetics of subsequent elongation. Here, with the benefit of the confinement from the layered double hydroxide (LDH) nanomaterial, various simple monomers, (such as benzene, naphthalene and pyrene derivatives) successfully form living supramolecular polymer (LSP) with length control and narrow dispersity. The degree of polymerization can reach ~6000. Kinetics studies reveal LDH overcomes a huge energy barrier to inhibit undesired spontaneous nucleation of monomers and disassembly of metastable states. The universality of this strategy will usher exploration into other multifunctional molecules and promote the development of functional LSP.

scholarly journals Initiation and propagation kinetics of inhibited lipid peroxidation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reza Farhoosh
Keyword(s):  
Lipid Peroxidation ◽  
Reverse Micelles ◽  
Fish Oils ◽  
Lipid Hydroperoxides ◽  
Critical Concentrations ◽  
Initial Values ◽  
Initiation And Propagation ◽  
Kinetics Of

AbstractEffect of hydroxytyrosol (HT) and tert-butylhydroquinone (TBHQ) on the kinetics of lipid hydroperoxides (LOOH) accumulation during the initiation and propagation peroxidations of canola and fish oils at 60 °C was studied. The initiation kinetics of the inhibited peroxidation indicated considerable relative activities, A, for HT and TBHQ in the canola (> 3200 and > 27,000, respectively) and fish (> 120 and > 5000, respectively) oils. The critical concentrations of LOOH reverse micelles (CMCL = 33 mM and 57 mM in the canola and fish, respectively, oils) significantly decreased, on average, to about one-third and 8% of the initial values for HT and TBHQ, respectively. Interestingly, the propagation kinetics of the inhibited peroxidation demonstrated that the antioxidants were still able to inhibit peroxidation, so that the relative propagation oxidizability parameter Rn′ was significantly improved to < 0.5 for HT and to < 0.2 for TBHQ in the canola and fish, respectively, oils.

scholarly journals Relationship of Exo-β-d-Galactofuranosidase Kinetic Parameters to the Number of Phosphodiesters in Penicillium fellutanum Peptidophosphogalactomannan: Enzyme Purification and Kinetics of Glycopeptide and Galactofuran Chain Hydrolysis

2001 ◽  
Vol 67 (10) ◽  
pp. 4648-4656 ◽  
Author(s):  
Brigitte A. Tuekam ◽  
Yong-Il Park ◽  
Clifford J. Unkefer ◽  
John E. Gander
Keyword(s):  
Kinetic Parameters ◽  
Kinetic Data ◽  
Inorganic Phosphate ◽  
Enzyme Purification ◽  
Degree Of Polymerization ◽  
Apparent Homogeneity ◽  
Relationship Of ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACT Extracellular Penicillium fellutanumexo-β-d-galactofuranosidase, with a mass of 70 kDa, was purified to apparent homogeneity. The enzyme was used to investigate the influence of phosphodiesters of the peptidophosphogalactomannans pP2GMii and pP25GMii(containing 2 and 25 phosphodiester residues, respectively, per mol of polymer) on the kinetic parameters of galactofuranosyl hydrolysis of these two polymers, of 1-O-methyl-β-d-galactofuranoside, and of two galactofuranooligosaccharides. The enzyme did not hydrolyze phosphorylated galactose residues of pP2GMii or pP25GMii. Thek cat/Km value for pP25GMii is 1.7 × 103M−1 s−1, that for 1-O-methyl-β-d-galactofuranoside is 1.1 × 104 M−1 s−1, that for pP2GMii is 1.7 × 10 4M−1 s−1, and those for 5-O-β-d-galactofuranooligosaccharides with degrees of polymerization of 3.4 and 5.5 are 1.7 × 105 and 4.1 × 105 M−1s−1, respectively. Variability in thek cat/Km values is due primarily to differences in Km values; thek −1/k 1 ratio likely provides the most influence on Km. k cat increases as the degree of polymerization of galactofuranosyl residues increases. Most of the galactofuranosyl and phosphocholine residues were removed by day 8 in vivo from pPxGMii added to day 3 cultures initiated in medium containing 2 mM phosphate but not from those initially containing 20 mM phosphate. The filtrates from day 9 cultures initiated in 2 mM inorganic phosphate in modified Raulin-Thom medium contained 0.2 mM inorganic phosphate and 2.2 U of galactofuranosidase ml−1h−1. No galactofuranosidase activity but 15 mM inorganic phosphate was found in filtrates from day 9 cultures initiated in 20 mM phosphate. In vivo the rate of galactofuranosyl hydrolysis of pPxGMii and of related polymers is proportional to thek cat/Km value of each polymer. The kinetic data show that thek cat/Km value increases as the number of phosphodiesters of pPxGMiidecreases, also resulting in an increase in the activity of exo-β-d-galactofuranosidase.

Mixed micelles of poly(styrene-b-3-(methacryloylamino)propyltrimethylammonium chloride-b-ethylene oxide) and anionic amphiphiles in aqueous solutions

2010 ◽  
Vol 88 (3) ◽  
pp. 208-216 ◽  
Author(s):  
Jingjing Liu ◽  
Airi Yoneda ◽  
Dian Liu ◽  
Yuuichi Yokoyama ◽  
Shin-ichi Yusa ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Aqueous Solutions ◽  
Mixed Micelles ◽  
Organic Dyes ◽  
Sodium Dodecyl ◽  
Degree Of Polymerization ◽  
Hydrodynamic Diameter ◽  
Low Concentration ◽  
Fluorescence Measurements ◽  
Kinetics Of

The micelles of poly(styrene-b-3-(methacryloylamino)propyltrimethylammonium chloride-b-ethylene oxide) (PS-b-PMAPTAC-b-PEO) have been successfully prepared in aqueous solutions. The micelles have a PS core, cationic PMAPTAC shell, and PEO corona. Due to the short PS chain (degree of polymerization = 8), the formation of micelles is difficult at a low concentration, and the micelles are detected only at concentrations higher than 1 g L–1. The addition of anionic amphiphiles, such as sodium dodecyl sulfate (SDS) and poly(methacrylic acid) (PMAA), induces the formation of mixed micelles at a low concentration level of the polymer (~0.005 g L–1). This can be ascribed to insolubilization of the cationic PMAPTAC block due to charge neutralization by the anionic amphiphiles. The binding of SDS or PMAA to the PMAPTAC block is confirmed by zeta-potential measurements. The mixed micelles are characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and fluorescence measurements. Based on DLS measurements, it is revealed that the hydrodynamic diameter of the mixed micelles falls in the range of 120–130 nm. SEM measurements provided clear pictures of mixed micelles with a spherical morphology. The kinetics of exchange of organic dyes between the micelle particles was investigated by fluorescence techniques. The result indicates that the exchange of the dyes between the micelle particles takes places within a time scale of seconds.

On the Mechanisms of Chemical Intercalation of Lithium in Electrode Materials

2017 ◽  
Vol 231 (7-8) ◽  
Author(s):  
Nele Isabell Schwarzburger ◽  
Harald Behrens ◽  
Ingo Horn ◽  
Michael Binnewies
Keyword(s):  
Isotope Exchange ◽  
Electrode Materials ◽  
Lithium Isotope ◽  
Butyl Lithium ◽  
Kinetics Of

Abstract:Reaction with n-butyl lithium (BuLi) is commonly used to study the kinetics of intercalation of lithium in electrode materials for batteries. We performed lithium isotope exchange experiments on TiS

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