On the Mechanism of Radical Polymerization of Methyl Methacrylate with Dithiobenzoic Acid as Mediator

2006 ◽  
Vol 59 (8) ◽  
pp. 549 ◽  
Author(s):  
Duc Hung Nguyen ◽  
Philipp Vana
Keyword(s):  
Methyl Methacrylate ◽  
Induction Period ◽  
Hydrogen Abstraction ◽  
Ester Group ◽  
Reaction Scheme ◽  
Ionization Mass ◽  
Controlled Polymerization ◽  
Induction Periods ◽  
Methyl Methacrylate Polymerization ◽  
Raft Agent

Dithiobenzoic acid (DTBA) induces controlled polymerization behaviour in methyl methacrylate polymerization at 60°C, accompanied by a pronounced induction period of several hours. DTBA is partially transformed during this induction period into a dithioester with a tertiary ester group moiety, which constitutes an efficient reversible addition–fragmentation chain transfer (RAFT) agent. The transformation reaction is proposed to proceed via a hydrogen abstraction from DTBA by radicals and subsequent termination of the formed phenylcarbonothioylsulfanyl radical with propagating radicals. The proposed reaction scheme was implemented into a computer model, by which the rate coefficient of the hydrogen abstraction from DTBA and of the reinitiation of the intermediate phenylcarbonothioylsulfanyl radical was estimated. The model is in agreement with all of the species observable by electrospray ionization mass spectrometry, with the extent of the experimental induction periods, and with the absolute concentrations of dithioesters that act as efficient RAFT agents during the polymerization. A protocol that uses a cocktail of initiators is introduced, by which the induction period in DTBA-mediated polymerization is effectively eliminated.

High Temperature Initiator-Free RAFT Polymerization of Methyl Methacrylate in a Microwave Reactor

2009 ◽  
Vol 62 (3) ◽  
pp. 254 ◽  
Author(s):  
Renzo M. Paulus ◽  
C. Remzi Becer ◽  
Richard Hoogenboom ◽  
Ulrich S. Schubert
Keyword(s):  
High Temperature ◽  
Methyl Methacrylate ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Linear Increase ◽  
Thermal Heating ◽  
Controlled Polymerization ◽  
Microwave Reactor ◽  
Reversible Addition ◽  
Raft Agent

The reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA) was investigated under microwave irradiation. At first, a comparison was made between microwave and thermal heating for the RAFT polymerization of MMA with azobis(isobutyronitrile) (AIBN) as initiator and 2-cyano-2-butyldithiobenzoate (CBDB) as RAFT agent, revealing comparable polymerization kinetics indicating the absence of non-thermal microwave effects. Second, the CBDB-mediated RAFT polymerization of MMA was investigated at high temperatures (120°C, 150°C, and 180°C, respectively) in the absence of a radical initiator, showing a linear increase of the molar masses with conversion. The polydispersity indices remained below 1.5 up to 25% MMA conversion at 120°C and 150°C, indicating a controlled polymerization. This control over the polymerization was confirmed by the ability to control the molar masses by the concentration of RAFT agent.

The effect of electrondonors on the polymerization kinetics of isoprene

1980 ◽  
Vol 45 (12) ◽  
pp. 3338-3346
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Induction Period ◽  
Ethyl Ether ◽  
Reaction Order ◽  
Propagation Rate ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Constant Concentration ◽  
Initial Concentration ◽  
Kinetics Of

The effect of small additions of 1-octene, butyl ethyl ether and triethylamine on the polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene initiated with butyllithium was investigated by employing the GLC analysis. The addition of 1-octane was reflected only in a shorter induction period of the reaction; the effect on the propagation rate was insignificant. With the increasing amount of butyl ethyl ether, the polymerization rate increases linearly, while the reaction order with respect to the concentration of triethylamine is variable and increases from 0.33 to 0.66 with the increasing concentration of the initiator. For a constant concentration of triethylamine, the reaction order with respect to the initial concentration of the initiator was found to vary considerably, reaching even negative values. A reaction scheme was suggested, taking into account the competition between two different solvates of alkyllithium.

Methyl methacrylate polymerization involving a cobalt ortho-iminobenzosemiquinone complex: Determination of the chain transfer constant

2015 ◽  
Vol 56 (3) ◽  
pp. 267-275 ◽  
Author(s):  
E. V. Kolyakina ◽  
Yu. E. Ovchinnikova ◽  
I. D. Grishin ◽  
A. I. Poddel’skii ◽  
D. F. Grishin
Keyword(s):  
Methyl Methacrylate ◽  
Chain Transfer ◽  
Transfer Constant ◽  
Methyl Methacrylate Polymerization ◽  
Chain Transfer Constant

Synthesis, Structure, and Methyl Methacrylate Polymerization Activity of a Mixed π-Ferrocene π-Toluene Complex of Potassium Tris(hexamethyldisilazide)magnesiate

2004 ◽  
Vol 23 (6) ◽  
pp. 1197-1199 ◽  
Author(s):  
Gordon W. Honeyman ◽  
Alan R. Kennedy ◽  
Robert E. Mulvey ◽  
David C. Sherrington
Keyword(s):  
Methyl Methacrylate ◽  
Methyl Methacrylate Polymerization

Shock-initiated exothermic reactions. VI. The oxidation of ethylene oxide and cyclopropane

1969 ◽  
Vol 22 (7) ◽  
pp. 1355 ◽  
Author(s):  
LJ Drummond ◽  
J Kikkert
Keyword(s):  
Shock Waves ◽  
Ethylene Oxide ◽  
Shock Tube ◽  
Induction Period ◽  
Ignition Delay ◽  
Exothermic Reactions ◽  
Induction Periods ◽  
Reflected Shock ◽  
Formaldehyde Oxidation ◽  
Temperature Dependences

Mixtures of ethylene oxide or cyclopropane with oxygen and argon were ignited with reflected shock waves In a shock tube. The temperature dependences of the ignition delay and the growth of light emitted during the induction period to explosion of C2H4O-O2 mixtures indicate that the rate-controlling reaction is that of formaldehyde oxidation. The temperature dependence of induction periods for C3H6-O2 mixtures suggests that a complicated but undetermined mechanism controls the delay to ignition.

scholarly journals Determination of oxidative stability in mixtures of edible oil with nonlipidic substances

2013 ◽  
Vol 19 (No. 1) ◽  
pp. 19-23 ◽  
Author(s):  
L. Trojáková ◽  
Z. Réblová ◽  
Z. Pokorný
Keyword(s):  
Induction Period ◽  
Oxygen Pressure ◽  
Rapeseed Oil ◽  
Lipid Fraction ◽  
Edible Oil ◽  
Sample Weight ◽  
Induction Periods ◽  
Hydrated Proteins ◽  
Working Day

The storage of lipid foods is mostly affected by the oxidation of lipid fraction. Dry foods are particularly sensitive because lipids are not protected by hydrated proteins against oxidation. A method suitable for testing dry foods was studied in model mixtures of rapeseed oil with albumin or cellulose. Oxipres apparatus was used, where the course of oxidation is monitored by changes of oxygen pressure. The end of induction period was more evident than in bulk oils as the contact of lipids with oxygen is better. The induction period was longer in mixtures of edible oil with albumin than in mixtures with cellulose. The induction period moderately decreased with increasing oxygen pressure, while the effect of sample weight was nearly negligible. The induction period length was a semilogarithmic function of reaction temperature. Variation coefficients and differences between the duplicates showed good reproducibility; they were lower in mixtures with albumin than in mixtures with cellulose, but both were of the same order as the respective values in bulk oils. At 120°C and 0.5 MPa oxygen, the induction periods could be usually measured within a working day.

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