TY - JOUR A1 - Jelicic, Aleksandra A1 - Garcia, Nuria A1 - Beuermann, Sabine T1 - Influence of ionic liquid structure on the propagation kinetics of methyl methacrylate Y1 - 2009 UR - http://pubs.acs.org/journal/mamobx U6 - https://doi.org/10.1021/ma900774e SN - 0024-9297 ER - TY - JOUR A1 - Siegmann, Rebekka A1 - Beuermann, Sabine T1 - Individual rate coefficients for 1H,1H,2H,2H-tridecafluorooctyl methacrylate radical polymerizations N2 - Kinetic data for radical polymerizations of 1H,1H,2H,2H-tridecafluorooctyl methacrylate (TDFOMA) in bulk is reported. Pulsed laser initiated polymerizations yield propagation rate coefficients, k(p), which are by a factor of 1.9 higher than methyl methacrylate k(p). The activation energy of TDFOMA k(p) is not significantly different from that of alkyl methacrylates. Chain-length averaged termination rate coefficients were estimated from chemically initiated polymerizations with in-line FT-NIR spectroscopic monitoring of monomer conversion. Up to 30% of monomer conversion TDFOMA termination rate coefficients are only slightly below MMA low conversion values. The result is suggested to be due to less interactions between the macroradicals compared to nonfluorinated systems. Y1 - 2010 UR - http://pubs.acs.org/journal/mamobx U6 - https://doi.org/10.1021/Ma902653b SN - 0024-9297 ER - TY - JOUR A1 - Vukicevic, Radovan A1 - Hierzenberger, Peter A1 - Hild, Sabine A1 - Beuermann, Sabine T1 - Functionalization of carbon black nanoparticles with poly(vinylidene fluoride) N2 - The surface of carbon black (CB) nanoparticles was functionalized with poly(vinylidene fluoride) (PVDF) either by trapping of macroradicals or by cycloaddition. PVDF with two iodine end groups (I-PVDF-I) obtained from iodine transfer polymerization in supercritical CO2 was heated in the presence of CB and the C-I bond was cleaved resulting in a reaction between the macroradical and the CB surface. To allow for cycloaddition of PVDF to the CB surface for a number of polymers, the iodine end groups were replaced by azide end groups. In addition, microwave irradiation was applied to the functionalization. The influence of temperature, time, polymer concentration, and polymer molar mass on the functionalization reaction was examined. Y1 - 2010 UR - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291542-9369 U6 - https://doi.org/10.1002/Pola.24277 SN - 0887-624X ER - TY - JOUR A1 - Jelicic, Aleksandra A1 - Garcia, Nuria A1 - Löhmannsröben, Hans-Gerd A1 - Beuermann, Sabine T1 - Prediction of the ionic liquid influence on propagation rate coefficients in methyl methacrylate radical polymerizations based on Kamlet-Taft solvatochromic parameters Y1 - 2009 UR - http://pubs.acs.org/journal/mamobx?cookieSet=1 U6 - https://doi.org/10.1021/ma9017907 SN - 0024-9297 ER - TY - JOUR A1 - Breininger, Eugenia A1 - Imran-ul-haq, Muhammad A1 - Tuerk, Michael A1 - Beuermann, Sabine T1 - Effect of polymer properties on poly(vinylidene fluoride) particles produced by rapid expansion of CO2 + polymer mixtures N2 - The generation of nanoscale primary poly(vinylidene fluoride) (PVDF) particles by rapid expansion of supercritical solutions (RESS) is reported. The experimental results show that RESS enables the formation of PVDF particles with median particle diameters ranging from 56 to 226 nm and that the size of PVDF particles can be influenced by polymer properties. The particle size can be decreased either by increasing molar mass, in case of identical polymer end groups, or by increasing the degree of crystallinity, in case of similar molar mass and different end groups. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/08968446 U6 - https://doi.org/10.1016/j.supflu.2008.09.016 SN - 0896-8446 ER - TY - JOUR A1 - Beuermann, Sabine T1 - Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations N2 - The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding or electron pair donor/acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, k(P), may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of k(P). In contrast, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in k(P). Y1 - 2009 UR - http://www3.interscience.wiley.com/cgi-bin/jhome/10003270 U6 - https://doi.org/10.1002/marc.200900131 SN - 1022-1336 ER - TY - JOUR A1 - Beuermann, Sabine T1 - Solvent influence on propagation kinetics in radical polymerizations studied by pulsed laser initiated polymerizations N2 - The influence of the reaction medium (organic solvents, water, ionic liquids, supercritical CO2) on the propagation rate in radical polymerizations has very different causes, e.g., hindered rotational modes, hydrogen bonding, or electron pair donor / acceptor interactions. Depending on the origin of the solvent influence propagation rate coefficients, kp, may be enhanced by up to an order of magnitude associated with changes in the pre-exponential or the activation energy of kp. Contrary, non-specific interactions, size and steric effects lead to rather small changes in the vicinity of the radical chain end and are reflected by modest variations in kp. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117932056/issueyeargroup?year=2009 SN - 1022-1336 ER - TY - JOUR A1 - Jelicic, Aleksandra A1 - Yasin, Muttaqin A1 - Beuermann, Sabine T1 - Toward the description and prediction of solvent induced variations in Methacrylate Propagation Rate Coefficients on the basis of Solvatochromic Parameters JF - Macromolecular reaction engineering N2 - Benzyl methacrylate (BzMA) propagation rate coefficients, k(p), were determined in ionic liquids and common organic solvents via pulsed-laser polymerizations with subsequent polymer analysis by size-exclusion chromatography (PLP-SEC). The aim of the work is to gain a deeper understanding of the solvent influence on k(p) and to develop a general correlation between solvent-induced variations in k(p) and solvent properties. Applying a linear solvation energy relationship (LSER), which correlates k(p) to solvent solvatochromic parameters, suggests that dipolarity/polarizability determines the solvent influence on k(p). To compare the solvent influence on BzMA k(p) with data for methyl methacrylate, hydroxypropyl methacrylate, and 2-ethoxyethyl methacrylate normalized k(p) data were treated by a single LSER, providing a universal treatment of the solvent influence on the propagation kinetics of the four monomers. Further, the predictive capabilities of this universal correlation were tested with additional monomers from the methacrylate family. KW - ionic liquid KW - kinetics (polym.) KW - radical polymerization KW - solvent influence Y1 - 2011 U6 - https://doi.org/10.1002/mren.201000058 SN - 1862-832X VL - 5 IS - 5-6 SP - 232 EP - 242 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Cockburn, Robert A. A1 - Siegmann, Rebekka A1 - Payne, Kevin A. A1 - Beuermann, Sabine A1 - McKenna, Timothy F. L. A1 - Hutchinson, Robin A. T1 - Free Radical Copolymerization Kinetics of gamma-Methyl-alpha-methylene-gamma-butyrolactone (MeMBL) JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - The propagation kinetics and copolymerization behavior of the biorenewable monomer gamma-methyl-alpha-methylene-gamma-butyrolactone (MeMBL) are studied using the Pulsed laser polymerization (PLP)/size exclusion chromatography (SEC) technique. The propagation rate coefficent for MeMBL is 15% higher than that of its structural analogue, methyl methacrylate (MMA), with a similar activation energy of 21.8 kJ . mol(-1). When compared to MMA, MeMBL is preferentially incorporated into copolymers when reacted with styrene (ST), MMA, and n-butyl acrylate (BA); the monomer reactivity ratios fit from bulk MeMBL/ST, MeMBL/MMA, and MeMBL/BA copolymerizations are r(MeMBL) = 0.80 +/- 0.04 and r(ST) = 0.34 +/- 0.04, r(MeMBL), = 3.0 +/- 0.3 and r(MMA) = 0.33 +/- 0.01, and r(MeMBL) = 7.0 +/- 2.0 and r(BA) = 0.16 +/- 0.03, respectively. In all cases, no significant variation with temperature was found between 50 and 90 degrees C. The implicit penultimate unit effect (IPUE) model was found to adequately fit the composition-averaged copolymerization propagation rate coefficient, k(p,cop), for the three systems. Y1 - 2011 U6 - https://doi.org/10.1021/bm200400s SN - 1525-7797 VL - 12 IS - 6 SP - 2319 EP - 2326 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Siegmann, Rebekka A1 - Möller, Eleonore A1 - Beuermann, Sabine T1 - Propagation rate coefficients for homogeneous phase VDF-HFP copolymerization in supercritical CO2 JF - Macromolecular rapid communications N2 - For the first time, propagation rate coefficients, kp,COPO, for the copolymerizations of vinylidene fluoride and hexafluoropropene have been determined. The kinetic data was determined via pulsed-laser polymerization in conjunction with polymer analysis via size-exclusion chromatography, the PLP-SEC technique. The experiments were carried out in homogeneous phase with supercritical CO2 as solvent for temperatures ranging from 45 to 90 degrees C. Absolute polymer molecular weights were calculated on the basis of experimentally determined MarkHouwink constants. The Arrhenius parameters of kp,COPO vary significantly compared with ethene, which is explained by the high electronegativity of fluorine and less intra- and intermolecular interactions between the partially fluorinated macroradicals. KW - copolymerization KW - fluorinated olefins KW - kinetics (polym) KW - pulse laser initiated polymerization KW - radical polymerization Y1 - 2012 U6 - https://doi.org/10.1002/marc.201200115 SN - 1022-1336 VL - 33 IS - 14 SP - 1208 EP - 1213 PB - Wiley-VCH CY - Weinheim ER -