Tertiary amine catalyzed photo-induced controlled radical polymerization of methacrylates

2015 ◽  
Vol 6 (30) ◽  
pp. 5362-5368 ◽  
Author(s):  
Qiang Fu ◽  
Thomas G. McKenzie ◽  
Shereen Tan ◽  
Eunhyung Nam ◽  
Greg G. Qiao
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Uv Irradiation ◽  
Tertiary Amine ◽  
Controlled Radical Polymerization ◽  
Low Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
End Group

A novel tertiary amine catalyst and trithiocarbonate synergistic photo-induced controlled radical polymerization of methacrylates has been realized under mild UV irradiation, yielding polymethacrylates with low molecular weight distributions and excellent end-group fidelity.

Visible-light induced controlled radical polymerization of methacrylates with Cu(dap)2Cl as a photoredox catalyst

2016 ◽  
Vol 7 (25) ◽  
pp. 4226-4236 ◽  
Author(s):  
Wenchao Ma ◽  
Dong Chen ◽  
Yuhong Ma ◽  
Li Wang ◽  
Changwen Zhao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Block Copolymers ◽  
Visible Light ◽  
Radical Polymerization ◽  
Visible Light Irradiation ◽  
Controlled Radical Polymerization ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
System P ◽  
Weight Distributions

Under visible light irradiation, block copolymers of PPEGMA-b-PMMA with high molecular weights and narrow molecular weight distributions are obtained starting from a PPEGMA macroinitiator in the presence of the Cu(dap)2Cl/Me6TREN catalytic system.

Characterization of Elution Chromatography Fractions from CIS-Polybutadiene by GPC

1970 ◽  
Vol 43 (6) ◽  
pp. 1439-1450 ◽  
Author(s):  
W. V. Smith ◽  
S. Thiruvengada
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Low Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Log Normal ◽  
Analytical Fractionation ◽  
Molecular Weight Fractions ◽  
Elution Chromatography

Abstract A preparative fractionation of about 23 g of a commercial cis-polybutadiene rubber is described. The method employed was a solvent elution chromatographic method with very little temperature gradient. The molecular weight distributions of the fractions obtained were determined by an analytical fractionation of 20 mg of polymer. The method was similar to the preparative fractionation and involved solvent elution chromatography. The fractions obtained were assayed for quantity, molecular weight, and molecular weight distribution by GPC. The low molecular weight fractions of the preparative fractionation had molecular weight distributions which could be closely approximated by two log normal distributions, the low molecular weight component having the narrower width. The ratio of weight to number average molecular weight was found to be about 1.1 for these samples. The higher molecular weight fractions could also be approximated by two log normal distributions; however, in these fractions the low molecular weight component had a very broad distribution but constituted only a small portion of the sample. The widths of the GPC curves of the fractions correlate satisfactorily with the molecular weight distributions found by the analytical refractionations. The GPC width is a sensitive criterion of the width of the molecular weight distribution even when only two columns are used. It is felt that the analytical fractionation procedure presented gives more detailed information on the molecular weight distribution than is easily obtainable from an ordinary GPC curve.

scholarly journals Tuning the molecular weight distribution from atom transfer radical polymerization using deep reinforcement learning

2018 ◽  
Vol 3 (3) ◽  
pp. 496-508 ◽  
Author(s):  
Haichen Li ◽  
Christopher R. Collins ◽  
Thomas G. Ribelli ◽  
Krzysztof Matyjaszewski ◽  
Geoffrey J. Gordon ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Reinforcement Learning ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Weight Distribution ◽  
In Silico ◽  
Atom Transfer ◽  
Polymer Molecular Weight ◽  
Molecular Weight Distributions ◽  
Weight Distributions

Combination of deep reinforcement learning and atom transfer radical polymerization gives precise in silico control on polymer molecular weight distributions.

Molecular Weight Determinations Of Low Molecular Weight (LMW) Heparins By Ultracentrifugation And High Pressure Liquid Chromatography

1981 ◽  
Author(s):  
Grant Barlow ◽  
N Sugisaka ◽  
F J Petracek
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Low Molecular Weight ◽  
Analytical Ultracentrifuge ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Heparin Fractions

Molecular weights were independently determined on nitrous acid depolymerized LMW heparin fractions ranging from 2-15 daltons using the analytical ultracentrifuge and high pressure liquid chromatography (HPLC).Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.Sedimentation-diffusion equilibria were obtained in the analytical ultracentrifuge using speeds ranging from 20,000 to 56,000 rpm. Near theta conditions were obtained using 0.5M NaCl as the solvent. Calculations of molecular weight distributions and, from those figures, weight average molecular weights were made using the method described by Scholte (N.Y. Acad Sci. 164, 156, 1969). The results show that weight average values as low as 2,000 daltons can be determined.The HPLC results were obtained using previously described methods (Fed Proc. 36, 89, 1977) and a new highly efficient gel column (TSK gels). Fractionated dextrans were used as reference standards.

scholarly journals Aqueous Photo-Living Radical Polymerization of Sodium Methacrylate Using a Water-Soluble Nitroxide Mediator

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Eri Yoshida
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Linear Correlation ◽  
Linear Increase ◽  
Living Radical Polymerization ◽  
Water Soluble ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Sodium Methacrylate

The aqueous photo-living radical polymerization of sodium methacrylate (NaMA) was attained using 2,2′-azobis2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]-propionamide (V-80) as the initiator and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (HTEMPO) as the mediator in the presence of (4-fluorophenyl)diphenylsulfonium triflate (FS). The polymerization was carried out in water at room temperature by irradiation using a high-pressure mercury lamp. Whereas the polymerization by V-80 and/or FS in the absence of HTEMPO produced polymers with very high molecular weights and broad molecular weight distributions, the HTEMPO-mediated polymerization provided still lower-molecular-weight distributions using both V-80 and FS. The first-order time-conversion plots had an induction period up to 2.5 h; however, they thereafter showed a linear increase. The conversion-molecular weight plots also exhibited a linear correlation. A linear correlation was also obtained for the plots of the molecular weights versus the reciprocal of the initiator concentration. Based on these three correlations, it was found that the HTEMPO-mediated photopolymerization proceeded by a living mechanism.

scholarly journals Further Effects of Chain-Length-Dependent Reactivities on Radical Polymerization Kinetics

2007 ◽  
Vol 60 (10) ◽  
pp. 754 ◽  
Author(s):  
Johan P. A. Heuts ◽  
Gregory T. Russell ◽  
Gregory B. Smith
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Chain Length ◽  
Chain Transfer ◽  
Transfer Constant ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
A Chain ◽  
Chain Transfer Constant ◽  
Independent Chain

In the present paper, we finalize some threads in our investigations into the effects of chain-length-dependent propagation (CLDP) on radical polymerization kinetics, confirming all our previous conclusions. Additionally, and more significantly, we uncover some unexpected and striking effects of chain-length-dependent chain transfer (CLDTr). It is found that the observed overall rate coefficients for propagation and termination (and therefore the rate of polymerization) are not significantly affected by whether or not chain transfer is chain-length dependent. However, this situation is different when considering the molecular weight distributions of the resulting polymers. In the case of chain-length-independent chain transfer, CLDP results in a considerable narrowing of the distribution at the low molecular weight side of the distribution in a chain-transfer controlled system. However, the inclusion of both CLDP and CLDTr yields identical results to classical kinetics – in these latter two cases, the molecular weight distribution is governed by the same chain-length-independent chain transfer constant, whereas in the case of CLDP only, it is governed by a chain-length-dependent chain transfer constant that decreases with decreasing chain length, thus enhancing the probability of propagation for short radicals. Furthermore, it is shown that the inclusion of a very slow first addition step has tremendous effects on the observed kinetics, increasing the primary radical concentration and thereby the overall termination rate coefficient dramatically. However, including possible penultimate unit effects does not significantly affect the overall picture and can be ignored for the time being. Lastly, we explore the prospects of using molecular weight distributions to probe the phenomena of CLDP and CLDTr. Again, some interesting insights follow.

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