On the molecular weight distribution polydispersity of continuous living-radical polymerization

2004 ◽  
Vol 92 (1) ◽  
pp. 539-542 ◽  
Author(s):  
F. Joseph Schork ◽  
Wilfred Smulders
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Living Radical Polymerization

The Application of Supercomputers in Modeling Chemical Reaction Kinetics: Kinetic Simulation of 'Quasi-Living' Radical Polymerization

1990 ◽  
Vol 43 (7) ◽  
pp. 1215 ◽  
Author(s):  
CHJ Johnson ◽  
G Moad ◽  
DH Solomon ◽  
TH Spurling ◽  
DJ Vearing
Keyword(s):  
Molecular Weight ◽  
Differential Equations ◽  
Radical Polymerization ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Euler Method ◽  
Living Radical Polymerization ◽  
Kinetic Simulation ◽  
Stiff Systems ◽  
Chemical Reaction Kinetics

A computer program has been written which employs an implicit Euler method to solve directly the complete set of coupled differential equations which result from an analysis of polymerization kinetics. The program was written to make full use of the speed and power of modern supercomputers, and is suited to the solution of very large stiff systems of differential equations. The benefit of treating each propagation step as a discrete reaction is that information on the evolution of the molecular weight distribution is obtained directly without the need to make perhaps unjustified assumptions such as the steady-state approximation. For illustrative purposes, the method has been applied in the kinetic simulation of 'quasi-living' radical polymerization to assess the effect of experimental variables on the molecular weight, molecular weight distribution, and rate of polymerization. The calculations show that 'quasi-living' radical polymerization can produce polymers with polydispersities approaching those obtained with anionic 'living' polymerizations. Some necessary conditions for the formation of polymers with narrow molecular weight distribution are defined.

scholarly journals Effects of Illuminance and Heat Rays on Photo-Controlled/Living Radical Polymerization Mediated by 4-Methoxy-2,2,6,6-Tetramethylpiperidine-1-Oxyl

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Eri Yoshida
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Light Source ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Bulk Polymerization ◽  
Living Radical Polymerization ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Controlled Living Radical Polymerization

The effects of illuminance and heat rays released from the light source on the photo-controlled/living radical polymerization of methyl methacrylate were investigated with the aim of strict control of molecular weight. The bulk polymerization was performed at room temperature using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator and (2RS,RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate as the accelerator by irradiation with a high-pressure mercury lamp. The polymerization by the direct irradiation from the light source yielded polymers containing an uncontrolled high-molecular-weight polymer and having the molecular weight distribution over 3. On the other hand, the polymerization by the indirect irradiation with reflective light using a mirror produced polymers with controlled molecular weights with comparatively narrow molecular weight distribution at ca. 1.4. Too high an illuminance caused an increase in the molecular weight distribution. During the polymerization, the monomer conversion increased as the illuminance increased. It was found that the elimination of heat rays from the illuminating light was indispensable for the molecular weight control by the photo-controlled/living radical polymerization.

Electrochemical Behaviors of Sulfurized-Polyacrylonitrile with Synthesized Polyacrylonitrile Precursors Based on the Radical Polymerization Through Monomer Acrylonitrile

2020 ◽  
Vol 20 (3) ◽  
pp. 1578-1588
Author(s):  
Si-Huang Peng ◽  
Shan-Shan Yao ◽  
Si-Kang Xue ◽  
Xin-Ye Qian ◽  
Xiang-Qian Shen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Electrochemical Performance ◽  
Radical Polymerization ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Infrared Spectrometry ◽  
Lithium Sulfur Battery ◽  
Composite Cathodes ◽  
Sulfur Battery ◽  
Lithium Sulfur

Polyacrylonitrile (PAN) precursors have been polymerized at different radical polymerization temperatures for preparing sulfurized-polyacrylonitrile (S-PAN) composite cathodes in rechargeable lithium sulfur battery. The physical properties of these composites have been investigated using X-ray diffraction, Fourier transform infrared spectrometry, Raman spectroscopy, Brunner-Emmet-Teller measurement and Gel permeation chromatography analysis. The electrochemical performance of the S-PAN composite cathodes made from the PAN precursor was investigated. The results showed that the molecular weight distribution of the PAN precursors affected the electrochemical performance of the S-PAN made from the PAN precursor. S-PAN composites derived from PAN with a narrower molecular weight distribution at 65 °C were exhibit the best electrochemical performance in lithium-sulfur battery.

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