0000000000706704

AUTHOR

Swaminathan Sivaram

showing 3 related works from this author

Effect of Lithium Perchlorate on the Kinetics of the Anionic Polymerization of Methyl Methacrylate in Tetrahydrofuran

1999

The kinetics of the anionic polymerization of methyl methacrylate in the presence of lithium perchlorate (LiClO 4 ) are investigated in THF using 1,1-diphenylhexyllithium as initiator in a flow-tube reactor between -30 and 0 °C. The rate constants of propagation determined in the presence of LiClO 4 are lower than those obtained in the absence of the salt, similar to the effect observed for LiCl. For propagation, the reaction order with respect to active center concentration is found to be 0.5 in both cases, which indicates that LiClO 4 does not effectively perturb the aggregation of the enolate ion pair. The formation of various mixed aggregates is proposed. The polydispersity index of the…

Order of reactionPolymers and PlasticsOrganic ChemistryInorganic chemistryKineticsSolution polymerizationLithium perchlorateInorganic Chemistrychemistry.chemical_compoundAnionic addition polymerizationReaction rate constantchemistryMaterials ChemistryMethyl methacrylateTetrahydrofuranMacromolecules
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Anionic Polymerization of Alkyl (Meth)acrylates Using Metal-Free Initiators:  Effect of Ion Pairing on Initiation Equilibria

1999

Metal-free anionic polymerizations of alkyl (meth)acrylates using tetrabutylammonium salts of diethylphenylmalonate, fluorene, and 9-ethylfluorene as initiators were performed in THF at 30 °C. A poor control of molecular weights, inconsistent initiator efficiencies, and broad or bimodal molecular weight distributions were obtained. The effect of counterion nature was studied from the polymerization of methyl methacrylate using the 1,1-diphenylhexyl anion with tetrabutylammonium, tetramethyldiethylguanidinium, and lithium as counterions under otherwise identical conditions. Metal-free initiators resulted in incomplete initiation which is attributed to the fact that the initiation is an equil…

chemistry.chemical_classificationPolymers and PlasticsOrganic ChemistrySolution polymerizationPolymerInorganic Chemistrychemistry.chemical_compoundAnionic addition polymerizationchemistryPolymerizationPolymer chemistryMaterials ChemistryHofmann eliminationCounterionMethyl methacrylateAlkylMacromolecules
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The effect of TMEDA on the kinetics of the anionic polymerization of methyl methacrylate in tetrahydrofuran using lithium as counterion

2000

The kinetics of the anionic polymerization of methyl methacrylate in presence of N,N,N', -tetramethylethylenediamine (TMEDA) in THF are investigated using 1,1-diphenyl-hexyllithium as initiator in a temperature range between -20°C and 0°C in a flow-tube reactor. The rate constants of propagation determined in the presence of TMEDA are compared to those obtained in the absence of a chelating agent. For propagation, the reaction order with respect to active centers is found to be 0.5 in both cases which indicates that the chelation of the lithium cation does not effectively perturb the aggregation of the enolate ion pair. Both the rate constants of propagation via non-aggregated ion pairs, k …

chemistry.chemical_classificationOrder of reactionPolymers and PlasticsOrganic ChemistrySolution polymerizationTetramethylethylenediamineCondensed Matter Physicschemistry.chemical_compoundAnionic addition polymerizationReaction rate constantchemistryPolymer chemistryMaterials ChemistryOrganic chemistryPhysical chemistryPhysical and Theoretical ChemistryCounterionTetrahydrofuranEquilibrium constant
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