García, Nuria

[["dc.bibliographiccitation.firstpage","3018"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Macromolecules"],["dc.bibliographiccitation.lastpage","3025"],["dc.bibliographiccitation.volume","37"],["dc.contributor.author","Beuermann, S."],["dc.contributor.author","Garcia, N."],["dc.date.accessioned","2018-11-07T10:49:36Z"],["dc.date.available","2018-11-07T10:49:36Z"],["dc.date.issued","2004"],["dc.description.abstract","Propagation kinetics of isobornyl methacrylate (iBoMA) and methyl methacrylate (MMA) free-radical homopolymerization were studied by the PLP-SEC method, which consists of pulsed laser initiated polymerizations and subsequent polymer analysis by size-exclusion chromatography. The reactions were carried out in bulk and in solution of several organic solvents: toluene, tetralin, tetrahydrofuran (THF), methyl isobutyrate, and phenethyl isobutyrate. In all polymerization systems, the activation energy of the observed propagation rate coefficient, k(p),(app), is not affected by either solvent type or solvent concentration. However, kp,app may be significantly different from the corresponding bulk values. In MMA polymerizations, kp,app values in solution were higher than in bulk, with the strongest enhancement of 50% observed for tetralin as solvent. In contrast, a solvent-induced lowering in propagation rate of up to 52% for THF as solvent was seen for iBoMA. The observed changes in propagation rate were assigned to the occurrence of a local monomer concentration in the vicinity of the free-radical chain end rather than to an intrinsic kinetic effect. The variation in local monomer concentrations is suggested to originate from differences in molar volume of the monomer and the solvent. Critical analysis of the results led to a linear correlation between solvent-induced changes in propagation rate and the difference in molar volumes of monomer and solvent. The correlation holds for both monomers."],["dc.identifier.doi","10.1021/ma035738q"],["dc.identifier.isi","000220898600047"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/48465"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Chemical Soc"],["dc.relation.issn","0024-9297"],["dc.title","A novel approach to the understanding of the solvent effects in radical polymerization propagation kinetics"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1338"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Macromolecular Chemistry and Physics"],["dc.bibliographiccitation.lastpage","1350"],["dc.bibliographiccitation.volume","204"],["dc.contributor.author","Beuermann, S."],["dc.contributor.author","Buback, M."],["dc.contributor.author","Davis, T. P."],["dc.contributor.author","Garcia, N."],["dc.contributor.author","Giess, Rene MarkusGilbert, Robert G."],["dc.contributor.author","Hutchinson, Robin A."],["dc.contributor.author","Kajiwara, A."],["dc.contributor.author","Kamachi, M."],["dc.contributor.author","Lacik, Igor"],["dc.contributor.author","Russell, Gregory T."],["dc.date.accessioned","2018-11-07T10:37:42Z"],["dc.date.available","2018-11-07T10:37:42Z"],["dc.date.issued","2003"],["dc.description.abstract","Propagation rate coefficients, k(p), which have been previously reported by several groups for free-radical bulk polymerizations of cyclohexyl methacrylate (CHMA), glycidyl methacrylate (GMA), benzyl methacrylate (BzMA), and isobomyl methacrylate (iBoMA) are critically evaluated. All data were determined by the combination of pulsed-laser polymerization (PLP) and subsequent polymer analysis by size-exclusion chromatography (SEC). This-so-called PLP-SEC technique has been recommended as the method of choice for the determination of k(p) by the IUPAC Working Party on Modeling of Polymerisation Kinetics and Processes. The present data fulfill consistency criteria and the agreement among the data from different laboratories is remarkable. The values for CHMA, GMA, and BzMA are therefore recommended as constituting benchmark data sets for each monomer. The data for iBoMA are also considered reliable, but since SEC calibration was established only by a single group, the data are not considered as a benchmark data set. All k(p) data for each monomer are best fitted by the following Arrhenius relations: CHMA: k(P) = 10(6.80) L . mol(-1) . s(-1) exp( -23.0 kJ.mol(-1) / (R.T), GMA: k(p) = 10(6.79) L . mol(-1) . s(-1) exp (-22.9 kJ.mol(-1)) / (R.T), BzMA: k(p) = 10(6.83) L . mol(-1) .s(-1) exp(-22.9 kJ.mol(-1)) / (R.T), iBoMA: k(p) =10(6.79)L . mol(-1) . s(-1) exp(-23.1 kJ.mol(-1)) / (R.T). Rather remarkably, for the methacrylates under investigation, the k(p) values are all very similar. Thus, all data can be fitted well by a single Arrhenius relation resulting in a pre-exponential factor of 4.24 x 10(6) L . mol(-1) . s(-1) and an activation energy of 21.9 kJ . mol(-1). All activation parameters refer to bulk polymerizations at ambient pressure and temperatures below 100degreesC. Joint confidence intervals are also provided, enabling values and uncertainties for k(p) to be estimated at any temperature."],["dc.identifier.doi","10.1002/macp.200390107"],["dc.identifier.isi","000184246300009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45634"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1022-1352"],["dc.title","Critically evaluated rate coefficients for free-radical polymerization, 4 - Propagation rate coefficients for methacrylates with cyclic ester groups"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]