Frauendorf, Holm

[["dc.bibliographiccitation.firstpage","5590"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","Polymer"],["dc.bibliographiccitation.lastpage","5598"],["dc.bibliographiccitation.volume","48"],["dc.contributor.author","Buback, Michael"],["dc.contributor.author","Frauendorf, Holm"],["dc.contributor.author","GUnzler, Fabian"],["dc.contributor.author","Vana, Philipp"],["dc.date.accessioned","2018-11-07T10:58:38Z"],["dc.date.available","2018-11-07T10:58:38Z"],["dc.date.issued","2007"],["dc.description.abstract","The type and number of end groups of poly(methyl methacrylates) from free-radical polymerization with six diacyl peroxides, R-(CO)O- O(CO)-R. acting as initiators have been analyzed via electrospray ionization mass spectrometry using an ion trap and additionally Fourier transform ion cyclotron resonance for mass detection. The polymerizations were carried out in benzene solution at high initiator concentration to yield low molecular weight polymer. With R being an alkyl group, only R moieties are observed as end groups. For each oligomer size, molecules with one or two such end groups are formed, depending on whether termination occurs via disproportionation or combination. With R being an aryl type, as in di-benzoyl and di-naphthoyl peroxides, both R and R-(CO)O moieties are detected as polymeric end groups. Because of aromatic delocalization. fractions of the arylic R-(CO)O-center dot radicals are sufficiently long living at 95 degrees C to add to a monomer molecule prior to undergo decarboxylation. (C) 2007 Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.polymer.2007.07.041"],["dc.identifier.isi","000250161000018"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/50507"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Sci Ltd"],["dc.relation.issn","0032-3861"],["dc.title","Electrospray ionization mass spectrometric end-group analysis of PMMA produced by radical polymerization using diacyl peroxide initiators"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","6071"],["dc.bibliographiccitation.issue","18"],["dc.bibliographiccitation.journal","Journal of Polymer Science Part A Polymer Chemistry"],["dc.bibliographiccitation.lastpage","6081"],["dc.bibliographiccitation.volume","46"],["dc.contributor.author","Buback, Michael"],["dc.contributor.author","Frauendorf, Holm"],["dc.contributor.author","Janssen, Olaf"],["dc.contributor.author","Vana, Philipp"],["dc.date.accessioned","2018-11-07T11:10:57Z"],["dc.date.available","2018-11-07T11:10:57Z"],["dc.date.issued","2008"],["dc.description.abstract","Initiation by diethyl peroxydicarbonate (E-PDC), di-n-tetradecyl peroxydicarbonate (nTD-PDC), di-n-hexadecyl peroxydicarbonate (nHD-PDC), and di-2-ethylhexyl peroxydicarbonate (2EH-PDC) of free-radical polymerizations of methyl methacrylate in benzene solution was studied by end-group analysis via electrospray ionization mass spectrometry (ESI-MS). Unambiguous assignment of ESI-MS peaks allows for identification of the type of radical that starts chain growth. In case of initiation by dialkyl peroxydicarbonates with linear alkyl groups, almost exclusively alkoxy carbonyloxyl species, which are the primary fragments from initiator decomposition, occur as end-groups. With 2EH-PDC, however, both the primary 2-ethylhexoxy carbonyloxyl fragment and a second moiety, which is formed by decarboxylation of the 2-ethylhexoxy carbonyloxyl radical, are clearly observed as end-groups. The decarboxylation process is described by a concerted mechanism which involves a 1,5-hydrogen shift reaction. (C) 2008 Wiley Periodicals, Inc."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [Bu 426/10-1]"],["dc.identifier.doi","10.1002/pola.22919"],["dc.identifier.isi","000259325100011"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/53320"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","John Wiley & Sons Inc"],["dc.relation.issn","0887-624X"],["dc.title","Electrospray ionization mass spectrometric study of end-groups in peroxydicarbonate-initiated radical polymerization"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1591"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","Macromolecular Chemistry and Physics"],["dc.bibliographiccitation.lastpage","1599"],["dc.bibliographiccitation.volume","210"],["dc.contributor.author","Buback, Michael"],["dc.contributor.author","Frauendorf, Holm"],["dc.contributor.author","Guenzler, Fabian"],["dc.contributor.author","Huff, Felix"],["dc.contributor.author","Vana, Philipp"],["dc.date.accessioned","2018-11-07T11:23:14Z"],["dc.date.available","2018-11-07T11:23:14Z"],["dc.date.issued","2009"],["dc.description.abstract","A method for measuring initiator efficiency in radical polymerization using ESI-MS is presented. The method is based on the evaluation of relative MS peak intensities of polymer that has been initiated by a mixture of initiators, of which one serves as an internal reference. The method is quickly and easily performed and was found to be reproducible and robust. In polymerization of methyl methacrylate in solution, the efficiency of BTMHP at 80 degrees C was determined to be f(BTMHP) =0.57 +/- 0.08, and the efficiency of DBPO at 100 degrees C was measured to be f(DBPO) = 0-89 +/- 0.08."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft [Bu 426/10-2]"],["dc.identifier.doi","10.1002/macp.200900237"],["dc.identifier.isi","000270859800003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/56155"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-v C H Verlag Gmbh"],["dc.relation.issn","1022-1352"],["dc.title","Determining Initiator Efficiency in Radical Polymerization by Electrospray-Ionization Mass Spectrometry"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2453"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","Journal of Polymer Science Part A Polymer Chemistry"],["dc.bibliographiccitation.lastpage","2467"],["dc.bibliographiccitation.volume","45"],["dc.contributor.author","Buback, Michael"],["dc.contributor.author","Frauendorf, Holm"],["dc.contributor.author","Guenzler, Fabian"],["dc.contributor.author","Vana, Philipp"],["dc.date.accessioned","2018-11-07T11:01:28Z"],["dc.date.available","2018-11-07T11:01:28Z"],["dc.date.issued","2007"],["dc.description.abstract","End-groups of poly(methyl methacrylate) from radical solution polymerization of MMA using tert-butyl peroxyacetate (TBPA), tert-amyl peroxyacetate (TAPA), 1,1,2,2tetramethylpropyl peroxyacetate (TMPPA), and 1,1,3,3-tetramethylbutyl peroxyacetate (TMBPA) as the initiators were analyzed via electrospray ionization mass spectrometry (ESI-MS). The type and the relative concentration of the radical species, which actually initiate macromolecular growth, are determined. In the majority of cases, these species differ from the primary radicals from thermal decomposition of the peroxyacetates. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was applied for unambiguous peak assignment. The methylearbonyloxyl radical, which is formed by the decomposition of all peroxyacetates, was found to undergo decarboxylation yielding an initiating methyl radical. TAPA- and TMPPA-derived alkoxyl radicals mainly show beta-scission, TMBPA-derived alkoxyl radicals additionally undergo a 1,5-hydrogen-shift reaction. The tert-butoxyl radicals produced from TBPA undergo pronounced chain-transfer reaction prior to their decomposition into methyl radicals and acetone. In the case of using benzene as a relatively inert solvent, the tert-butoxyl radicals exhibit transfer to monomer yielding polymer molecules, which do not carry any initiator-derived end-groups. By using mesitylene as a cosolvent, small amounts of star polymer were generated via multiple hydrogen abstraction by tert-butoxyl radicals from the three individual methyl groups of mesitylene. This uncomplicated procedure of modification of end-group and polymer topology may be attractive for facile adjustment of polymer viscosity in technical processes. (C) 2007 Wiley Periodicals, Inc."],["dc.identifier.doi","10.1002/pola.22008"],["dc.identifier.isi","000246894100010"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51156"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","John Wiley & Sons Inc"],["dc.relation.issn","0887-624X"],["dc.title","Initiation of radical polymerization by peroxyacetates: Polymer end-group analysis by electrospray ionization mass spectrometry"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]