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.

Kinetics of Supramolecular Polymerization: MSOA and HG Mechanisms

2006 ◽  
Vol 11-12 ◽  
pp. 639-642
Author(s):  
Yan Li Fan ◽  
Hao Jin ◽  
Xiao Hua Zhi ◽  
Ya Fei Lu
Keyword(s):  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Supramolecular Polymer ◽  
Helical Polymer ◽  
Repeat Units ◽  
Helical Growth ◽  
Step Growth ◽  
Supramolecular Polymerization ◽  
Kinetics Of ◽  
Supramolecular Chains

Multistage open association (MSOA) and helical growth (HG) mechanisms describe the linear growth of supramolecular polymer chains and the helical growth of supramolecular chains with the intra-assemble cooperative effect, respectively. Both mechanisms were proposed by Ciferri. Assuming that supramolecular polymerization follows the step-growth and the interaction between repeat units is independent of molecular weight, the kinetics of MSOA and HG can be mathematically analyzed. In this paper the relationships among degree of polymerization (DP), unimer concentration (C0), and equilibrium constant (K) for MSOA and DP , concentration of helical polymer ( h C ), and nucleation factor (σ ) for HG were derived.

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 A Comparative Study on Cure Kinetics of Layered Double Hydroxide (LDH)/Epoxy Nanocomposites

2020 ◽  
Vol 4 (3) ◽  
pp. 111
Author(s):  
Zohre Karami ◽  
Seyed Mohammad Reza Paran ◽  
Poornima Vijayan P. ◽  
Mohammad Reza Ganjali ◽  
Maryam Jouyandeh ◽  
...  
Keyword(s):  
Layered Double Hydroxide ◽  
Cure Kinetics ◽  
Frequency Factor ◽  
Isoconversional Methods ◽  
Epoxide Ring ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Noncatalytic Reaction ◽  
Double Hydroxide ◽  
Kinetics Of

Layered double hydroxide (LDH) minerals are promising candidates for developing polymer nanocomposites and the exchange of intercalating anions and metal ions in the LDH structure considerably affects their ultimate properties. Despite the fact that the synthesis of various kinds of LDHs has been the subject of numerous studies, the cure kinetics of LDH-based thermoset polymer composites has rarely been investigated. Herein, binary and ternary structures, including [Mg0.75 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, [Mg0.75 Al0.25 (OH)2]0.25+ [(NO3−)0.25∙m H2O]0.25− and [Mg0.64 Zn0.11 Al0.25 (OH)2]0.25+ [(CO32−)0.25/2∙m H2O]0.25−, have been incorporated into epoxy to study the cure kinetics of the resulting nanocomposites by differential scanning calorimetry (DSC). Both integral and differential isoconversional methods serve to study the non-isothermal curing reactions of epoxy nanocomposites. The effects of carbonate and nitrate ions as intercalating agents on the cure kinetics are also discussed. The activation energy of cure (Eα) was calculated based on the Friedman and Kissinger–Akahira–Sunose (KAS) methods for epoxy/LDH nanocomposites. The order of autocatalytic reaction (m) for the epoxy/Mg-Al-NO3 (0.30 and 0.254 calculated by the Friedman and KAS methods, respectively) was smaller than that of the neat epoxy, which suggested a shift of the curing mechanism from an autocatalytic to noncatalytic reaction. Moreover, a higher frequency factor for the aforementioned nanocomposite suggests that the incorporation of Mg-Al-NO3 in the epoxy composite improved the curability of the epoxy. The results elucidate that the intercalating anions and the metal constituent of LDH significantly govern the cure kinetics of epoxy by the participation of nitrate anions in the epoxide ring-opening reaction.

High Degree of Polymerization in a Fullerene-Containing Supramolecular Polymer

2014 ◽  
Vol 126 (22) ◽  
pp. 5735-5739 ◽  
Author(s):  
Helena Isla ◽  
Emilio M. Pérez ◽  
Nazario Martín
Keyword(s):  
Degree Of Polymerization ◽  
Supramolecular Polymer ◽  
High Degree

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.

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