@article{SchmidtBehlLendleinetal.2014,
  author    = {Schmidt, Christian and Behl, Marc and Lendlein, Andreas and Beuermann, Sabine},
  title     = {Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide},
  series = {RSC Advances},
  volume    = {4},
  journal   = {RSC Advances},
  number    = {66},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c4ra06815g},
  pages     = {35099 -- 35105},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{MoellerBeuermann2011,
  author    = {M{\"o}ller, Eleonore and Beuermann, Sabine},
  title     = {Homogeneous phase copolymerizations of vinylidene fluoride and hexafluoropropene in supercritical carbon dioxide},
  series = {Macromolecular reaction engineering},
  volume    = {5},
  journal   = {Macromolecular reaction engineering},
  number    = {1},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1862-832X},
  doi       = {10.1002/mren.201000031},
  pages     = {8 -- 21},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{SchreiberHosemannBeuermann2011,
  author    = {Schreiber, Ulrike and Hosemann, Benjamin and Beuermann, Sabine},
  title     = {1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP},
  series = {Macromolecular chemistry and physics},
  volume    = {212},
  journal   = {Macromolecular chemistry and physics},
  number    = {2},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201000307},
  pages     = {168 -- 179},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{VukicevicBeuermann2011,
  author    = {Vukicevic, Radovan and Beuermann, Sabine},
  title     = {Fullerenes decorated with poly(vinylidene fluoride)},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {44},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  number    = {8},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/ma102754c},
  pages     = {2597 -- 2603},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{CockburnSiegmannPayneetal.2011,
  author    = {Cockburn, Robert A. and Siegmann, Rebekka and Payne, Kevin A. and Beuermann, Sabine and McKenna, Timothy F. L. and Hutchinson, Robin A.},
  title     = {Free Radical Copolymerization Kinetics of gamma-Methyl-alpha-methylene-gamma-butyrolactone (MeMBL)},
  series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences},
  volume    = {12},
  journal   = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences},
  number    = {6},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1525-7797},
  doi       = {10.1021/bm200400s},
  pages     = {2319 -- 2326},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{JelicicYasinBeuermann2011,
  author    = {Jelicic, Aleksandra and Yasin, Muttaqin and Beuermann, Sabine},
  title     = {Toward the description and prediction of solvent induced variations in Methacrylate Propagation Rate Coefficients on the basis of Solvatochromic Parameters},
  series = {Macromolecular reaction engineering},
  volume    = {5},
  journal   = {Macromolecular reaction engineering},
  number    = {5-6},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1862-832X},
  doi       = {10.1002/mren.201000058},
  pages     = {232 -- 242},
  year      = {2011},
  abstract  = {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.},
  language  = {en}
}
@article{VukicevicSchwadtkeSchmueckeretal.2012,
  author    = {Vukicevic, Radovan and Schwadtke, Ulrike and Schmuecker, Simon and Schaefer, Philipp and Kuckling, Dirk and Beuermann, Sabine},
  title     = {Alkyne-azide coupling of tailored poly(vinylidene fluoride) and polystyrene for the synthesis of block copolymers},
  series = {Polymer Chemistry},
  volume    = {3},
  journal   = {Polymer Chemistry},
  number    = {2},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1759-9954},
  doi       = {10.1039/c1py00427a},
  pages     = {409 -- 414},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{VukicevicVukovicStoyanovetal.2012,
  author    = {Vukicevic, Radovan and Vukovic, Ivana and Stoyanov, Hristiyan and Korwitz, Andreas and Pospiech, Doris and Kofod, Guggi and Loos, Katja and ten Brinke, Gerrit and Beuermann, Sabine},
  title     = {Poly(vinylidene fluoride)-functionalized single-walled carbon nanotubes for the preparation of composites with improved conductivity},
  series = {Polymer Chemistry},
  volume    = {3},
  journal   = {Polymer Chemistry},
  number    = {8},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1759-9954},
  doi       = {10.1039/c2py20166f},
  pages     = {2261 -- 2265},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{BarthSiegmannBeuermannetal.2012,
  author    = {Barth, Johannes and Siegmann, Rebekka and Beuermann, Sabine and Russell, Gregory T. and Buback, Michael},
  title     = {Investigations into chain-length-dependent termination in bulk radical polymerization of 1H, 1H, 2H, 2H-Tridecafluorooctyl methacrylate},
  series = {Macromolecular chemistry and physics},
  volume    = {213},
  journal   = {Macromolecular chemistry and physics},
  number    = {1},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201100479},
  pages     = {19 -- 28},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{SiegmannMoellerBeuermann2012,
  author    = {Siegmann, Rebekka and M{\"o}ller, Eleonore and Beuermann, Sabine},
  title     = {Propagation rate coefficients for homogeneous phase VDF-HFP copolymerization in supercritical CO2},
  series = {Macromolecular rapid communications},
  volume    = {33},
  journal   = {Macromolecular rapid communications},
  number    = {14},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1336},
  doi       = {10.1002/marc.201200115},
  pages     = {1208 -- 1213},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}