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 - TY - JOUR A1 - Vukicevic, Radovan A1 - Vukovic, Ivana A1 - Stoyanov, Hristiyan A1 - Korwitz, Andreas A1 - Pospiech, Doris A1 - Kofod, Guggi A1 - Loos, Katja A1 - ten Brinke, Gerrit A1 - Beuermann, Sabine T1 - Poly(vinylidene fluoride)-functionalized single-walled carbon nanotubes for the preparation of composites with improved conductivity JF - Polymer Chemistry N2 - The surface of single-walled carbon nanotubes (SWCNTs) was functionalized with azide-terminated poly(vinylidene fluoride) (PVDF). Functionalization was confirmed by dispersibility, Raman spectroscopy, and thermogravimetric analyses. Raman spectra show disordering of the SWCNTs, thus, strongly suggesting that PVDF was covalently attached to SWCNTs. Functionalized SWCNTs were mixed with commercially available PVDF in a twin-screw extruder and thin films were obtained by melt-pressing. Films containing 0.5 and 1 wt% PVDF-functionalized SWCNTs exhibited significantly improved electrical conductivity compared to PVDF films containing pristine SWCNTs. Y1 - 2012 U6 - https://doi.org/10.1039/c2py20166f SN - 1759-9954 VL - 3 IS - 8 SP - 2261 EP - 2265 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Vukicevic, Radovan A1 - Beuermann, Sabine T1 - Fullerenes decorated with poly(vinylidene fluoride) JF - Macromolecules : a publication of the American Chemical Society N2 - Fullerenes decorated with poly(vinylidene fluoride) (PVDF) were synthesized in a three-step procedure: Iodine transfer polymerization of vinylidene fluoride with C(6)F(12)I(2) as the chain transfer agent was carried out in supercritical carbon dioxide to synthesize iodine-terminated PVDF, which was subsequently transformed to azide-terminated polymer. Finally, azide-terminated PVDF chains were attached to a fullerene core under microwave irradiation at 160 degrees C in 1.5 h. The materials were characterized by NMR, FT-IR, UV/vis, GPC, elemental analysis, and DSC. On average, 4-5 PVDF chains are attached to one C(60) moiety. FT-IR spectra and DSC measurements indicate that the polymer end groups strongly affect the crystallinity of the material. For PVDF with azide end groups and PVDF attached to fullerenes the fraction of the beta polymorph is dominant while alpha polymorphs are almost absent. Y1 - 2011 U6 - https://doi.org/10.1021/ma102754c SN - 0024-9297 VL - 44 IS - 8 SP - 2597 EP - 2603 PB - American Chemical Society CY - Washington ER - TY - CHAP A1 - Vukicevic, Radovan A1 - Schreiber, Ulrike A1 - Beuermann, Sabine T1 - Azide-terminated poly(vinylidene fluoride) as building block for nanocomposite materials and block copolymers T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2011 SN - 0065-7727 VL - 242 IS - 16 PB - American Chemical Society CY - Washington ER - TY - CHAP A1 - Schreiber, Ulrike A1 - Vukicevic, Radovan A1 - Beuermann, Sabine T1 - Block copolymers of poly(vinylidene fluoride) obtained via 1,3 dipolar cycloaddition T2 - Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS Y1 - 2011 SN - 0065-7727 VL - 242 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Barth, Johannes A1 - Siegmann, Rebekka A1 - Beuermann, Sabine A1 - Russell, Gregory T. A1 - Buback, Michael T1 - Investigations into chain-length-dependent termination in bulk radical polymerization of 1H, 1H, 2H, 2H-Tridecafluorooctyl methacrylate JF - Macromolecular chemistry and physics N2 - The SP-PLP-EPR technique is used to carry out a detailed investigation of the radical termination kinetics of 1H, 1H, 2H, 2H-tridecafluorooctyl methacrylate (TDFOMA) in bulk at relatively low conversion. Composite-model behavior for chain-length-dependent termination rate coefficients, kti,i, is observed. It is found that for TDFOMA, ic approximate to 60 independent of temperature, and as approximate to 0.65 and al approximate to 0.2 at 80 degrees C and above. However, at lower temperatures the situation is strikingly different, with the significantly higher average values of as = 0.89 +/- 0.15 and al = 0.32 +/- 0.10 being obtained at 50 degrees C and below. This makes TDFOMA the first monomer to be found that exhibits clearly different exponent values, as and al, at lower and higher temperature, and that has both a high as, like an acrylate, and a high ic, like a methacrylate. KW - ESR KW - EPR KW - kinetics (polym KW - ) KW - methacrylates KW - radical polymerization KW - termination Y1 - 2012 U6 - https://doi.org/10.1002/macp.201100479 SN - 1022-1352 VL - 213 IS - 1 SP - 19 EP - 28 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Vukicevic, Radovan A1 - Schwadtke, Ulrike A1 - Schmuecker, Simon A1 - Schaefer, Philipp A1 - Kuckling, Dirk A1 - Beuermann, Sabine T1 - Alkyne-azide coupling of tailored poly(vinylidene fluoride) and polystyrene for the synthesis of block copolymers JF - Polymer Chemistry N2 - The synthesis of block copolymers consisting of poly(vinylidene fluoride) (PVDF) and polystyrene (PS) is reported. Firstly, a propargyl-functionalized alkoxyamine initiator (PgOTIPNO) was prepared and subsequently used for the preparation of a propargyl-terminated PS homopolymer of different chain lengths with low dispersities via nitroxide-mediated radical polymerization. A tailored PVDF homopolymer with iodine end groups originating from iodine transfer polymerization was transformed to PVDF with azide end group. Then, alkyne-terminated PS with different molecular weights and azide-terminated PVDF were joined together via copper-catalyzed alkyne-azide coupling. The block copolymers were characterized using H-1-NMR, F-19-NMR, IR, SEC, and DSC. Y1 - 2012 U6 - https://doi.org/10.1039/c1py00427a SN - 1759-9954 VL - 3 IS - 2 SP - 409 EP - 414 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Möller, Eleonore A1 - Beuermann, Sabine T1 - Homogeneous phase copolymerizations of vinylidene fluoride and hexafluoropropene in supercritical carbon dioxide JF - Macromolecular reaction engineering N2 - Copolymerizations of vinylidene fluoride (VDF) and hexafluoropropene (HFP) were carried out in homogeneous phase with supercritical carbon dioxide up to complete VDF conversion using conventional peroxide initiators. The HFP monomer feed ratios, f(HFP), were varied between 0.65 and 0.20. Depending on f(HFP) amorphous or semi-crystalline copolymers were obtained. f(HFP) also determines the minimum pressure required to allow for homogeneous phase reactions. For example, HFP-rich copolymerizations in 70 wt.-% CO(2) at 100 degrees C require a pressure of around 500 bar. Further, bulk copolymerizations in homogenous phase were feasible for f(HFP) 0.65 at 900 bar up to complete VDF conversion. Copolymerizations in the presence of perfluorinated hexyl iodide carried out at 75 degrees C gave access to low dispersity polymers. Due to homogeneous phase conditions the use of any surfactants or fluorinated cosolvent is avoided. KW - copolymerization KW - hexafluoropropene KW - phase behavior KW - supercritical CO(2) KW - vinylidene fluoride Y1 - 2011 U6 - https://doi.org/10.1002/mren.201000031 SN - 1862-832X VL - 5 IS - 1 SP - 8 EP - 21 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schreiber, Ulrike A1 - Hosemann, Benjamin A1 - Beuermann, Sabine T1 - 1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP JF - Macromolecular chemistry and physics N2 - Block copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (AC8) were obtained from ARGET ATRP. To obtain block copolymers of low dispersity the PAC8 block was synthesized in anisole with a CuBr(2)/PMDETA catalyst in the presence of tin(II) 2-ethylhexanoate as a reducing agent. The PAC8 block was subsequently used as macroinitiator for copolymerization with butyl and tert-butyl acrylate carried out in scCO(2). To achieve catalyst solubility in CO(2) two fluorinated ligands were employed. The formation of block copolymers was confirmed by size exclusion chromatography and DSC. KW - atom transfer radical polymerization (ATRP) KW - block copolymers KW - fluoropolymers KW - supercritical carbon dioxide Y1 - 2011 U6 - https://doi.org/10.1002/macp.201000307 SN - 1022-1352 VL - 212 IS - 2 SP - 168 EP - 179 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Christian A1 - Behl, Marc A1 - Lendlein, Andreas A1 - Beuermann, Sabine T1 - Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide JF - RSC Advances N2 - Polyglycolide (PGA) is a biodegradable polymer with multiple applications in the medical sector. Here the synthesis of high molecular weight polyglycolide by ring-opening polymerization of diglycolide is reported. For the first time stabilizer free supercritical carbon dioxide (scCO(2)) was used as a reaction medium. scCO(2) allowed for a reduction in reaction temperature compared to conventional processes. Together with the lowering of monomer concentration and consequently reduced heat generation compared to bulk reactions thermal decomposition of the product occurring already during polymerization is strongly reduced. The reaction temperatures and pressures were varied between 120 and 150 degrees C and 145 to 1400 bar. Tin(II) ethyl hexanoate and 1-dodecanol were used as catalyst and initiator, respectively. The highest number average molecular weight of 31 200 g mol(-1) was obtained in 5 hours from polymerization at 120 degrees C and 530 bar. In all cases the products were obtained as a dry white powder. Remarkably, independent of molecular weight the melting temperatures were always at (219 +/- 2)degrees C. Y1 - 2014 U6 - https://doi.org/10.1039/c4ra06815g SN - 2046-2069 VL - 4 IS - 66 SP - 35099 EP - 35105 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Xie, Zai-Lai A1 - Jelicic, Aleksandra A1 - Wang, Feipeng A1 - Rabu, Pierre A1 - Friedrich, Alwin A1 - Beuermann, Sabine A1 - Taubert, Andreas T1 - Transparent, flexible, and paramagnetic ionogels based on PMMA and the iron-based ionic liquid 1-butyl-3- methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] N2 - The iron-containing ionic liquid (IL) 1-butyl-3-methylimidazolium tetrachloroferrate(III) [Bmim][FeCl4] has been used as a building block in the synthesis of transparent, ion-conducting, and paramagnetic ionogels. UV/Vis spectroscopy shows that the coordination around the Fe(III) ion does slightly change upon incorporation of the IL into PMMA. The thermal stability of the PMMA increases significantly with IL incorporation. In particular, the onset weight loss observed at ca. 265 degrees C for pure PMMA is completely suppressed. The ionic conductivity shows a strong temperature dependence and increases with increasing IL weight fractions. The magnetic properties are similar to those reported for the pure IL and are not affected by the incorporation into the PMMA matrix. The resulting ionogel is thus an interesting prototype for soft, flexible, and transparent materials combining the mechanical properties of the matrix with the functionality of the metal-containing IL, such as magnetism. Y1 - 2010 UR - http://www.rsc.org/Publishing/Journals/jm/index.asp U6 - https://doi.org/10.1039/C0jm01733g SN - 0959-9428 ER -