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  - 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  - 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  -