Using 1H‐NMR spectroscopy for the kinetic study of the in situ solution free‐radical copolymerization of styrene and ethyl acrylate (original) (raw)
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Kinetic Investigation and Characterization of Styrene-Butyl Acrylate Solution Copolymerization
1999
An investigation on the kinetics of free radical solution copolymerization of styrene with butyl acrylate using benzoyl peroxide and toluene, was made at 80 'C using fixed initiator and solvent concentrations . Sequence distribution of styrene and butyl acrylate and determination of copolymer composition by IH NMR and 73 C NMR are reported . By interpretation of the t3C NMR spectra of the homopolymers and copolymers, assignment of the carbonyl and quart- emary carbon atom resonances has been made . It has been then possible to make a quantitative estimation of the compositional triad distributions in the copolymers . The results are found to be in relatively good agreement with calculated triad sequences.
Journal of Applied Polymer …, 2009
Atom transfer radical bulk copolymerization of styrene (St) and methyl acrylate (MA) initiated with trichloromethyl-terminated poly(vinyl acetate) macroinitiator was performed in the presence of CuCl/PMDETA as a catalyst system at 90 C. Linear dependence of ln[M] 0 /[M] versus time data along with narrow polydispersity of molecular weight distribution revealed that all the homoand copolymerization reactions proceed according to the controlled/living characteristic. To obtain more reliable monomer reactivity ratios, the cumulative average copolymer composition at moderate to high conversion was determined by 1 H-NMR spectroscopy. Reactivity ratios of St and MA were calculated by the extended Kelen-Tudos (KT) and Mao-Huglin (MH) methods to be r St ¼ 1.018 AE 0.060, r MA ¼ 0.177 AE 0.025 and r St ¼ 1.016 AE 0.053, r MA ¼ 0.179 AE 0.023, respectively, which are in a good agreement with those reported for the conventional free-radical copolymerization of St and MA. Good agreement between the theoretical and experimental composition drifts in the comonomer mixture and copolymer as a function of the overall monomer conversion were observed, indicating that the reactivity ratios calculated by copolymer composition at the moderate to high conversion are accurate. Instantaneous copolymer composition curve and number-average sequence length of comonomers in the copolymer indicated that the copolymerization system tends to produce a random copolymer. However, MA-centered triad distribution results indicate that the spontaneous gradient copolymers can also be obtained when the mole fraction of MA in the initial comonomer mixture is high enough.
A kinetic study of free radical copolymerization of styrene/butyl acrylate
Macromolecular Chemistry and Physics, 1999
The variation of copolymerization rate with composition obtained for the system methyl acrylate (l)/methyl methacrylate (2)/benzene/2,2'-azoisobutyronitrile using standard techniques of polymerization rate measurements has been interpreted on the basis of a penultimate effect upon the propagation reaction, giving values of s, = 0.547 and s2 = 1.668 for the chain-end reactivity ratios.
Journal of applied …, 2006
Here, online 1 H-NMR spectroscopy has been successfully applied to investigate the kinetic parameters of radical copolymerization of styrene (St) and itaconic acid (IA). This technique was used because it allowed us to individually map out the monomer conversions of St and IA during the course of the polymerization at various conversions. This was possible because the individual contributions to the overall monomer conversion from St and IA could be measured through their nonoverlapping vinylic proton signals. The results of monomer conversion during the time in the corresponding 1 H-NMR spectra was the basis of our analysis to determine the reactivity ratios of St and IA in the solution and radical copolymerization reaction by several methods. In addition to linear least-squares methods, such as Finemann-Ross, inverted Finemann-Ross, Mayo-Lewis, Kelen-Tudos, extended Kelen-Tudos, and Mao-Huglin, a nonlinear least-square method (Tidwell-Mortimer) was used for this purpose, at low conversions. Extended Kelen-Tudos and Mao-Huglin were applied to determine the reactivity ratio values at high conversions too.
Macromolecules
A model system of styrene (St) and methyl methacrylate (MMA) was copolymerized in an NMR tube at 60°C using 2,2′-azobis(isobutyronitrile) as the initiator and pyridazine as an internal standard to optimize an in situ 1 H NMR spectroscopic method for determining reactivity ratios by generating data at hundreds of instantaneous comonomer compositions (244 data points from 8 to 91 mol % St) starting with only nine initial comonomer compositions. The radical reactivity ratios of styrene (r St = 0.697 ± 0.010) and methyl methacrylate (r MMA = 0.491 ± 0.007) were determined by nonlinear least-squares fitting of a Mayo−Lewis plot of the instantaneous copolymer composition as a function of the comonomer feed composition using the terminal model and MINITAB statistical software, in which the copolymer composition was calculated by assuming that all comonomer consumed was converted to copolymer without side reactions; the results were similar to accepted literature values for the terminal and implicit penultimate models. After correcting for changes in the "lock" value at the initial stages of the copolymerization (because of solids formed in the sealed NMR tube), the same technique was used to determine the reactivity ratios of 2-(N-ethylperfluorooctanesulfonamido)ethyl acrylate (FOSA; r FOSA = 1.624 ± 0.048) and 2-(N-ethylperfluorooctanesulfonamido)ethyl methacrylate (FOSM; r FOSM = 2.876 ± 0.083) in their radical copolymerizations with N,Ndimethylacrylamide (DMA; r DMA = 1.126 ± 0.031 with FOSA; r DMA = 0.859 ± 0.026 with FOSM).
European Polymer Journal, 2003
Octyl acrylate and styrene (OA-St) were copolymerized by conventional polymerization at 80°C and atom transfer radical polymerizations at 130°C in different feed ratios (0.1-0.9 mole fraction of OA) using benzoyl peroxide and cuprous chloride/2,2 0 -bipyridine/1-phenyl ethyl chloride respectively. Two linear (Fineman-Ross, Kelen-T€ u ud€ o os) methods and a nonlinear least-squares method were employed for determination of monomer reactivity ratios (r OA ¼ 0:30 AE 0:02 and r St ¼ 0:69 AE 0:04). Integrated intensities of the three peaks observed in the 1 H NMR spectra of -OCH 2 group (3.2-4.2 ppm) were used to determine the mole fraction of 111, 112 or 211 and 212 triad sequences in the copolymers. In addition, the r OA value was used for theoretical determination of mole fraction of these triad sequences. Well-agreed theoretical and experimental values helped us in determining most probable mole fractions of the triad sequences of monomers.
Journal of Polymer Science Part A: Polymer Chemistry, 2004
Enthalpic and electronic terminal and penultimate unit effects in the free-radical copolymerization of styrene (S) with methyl methacrylate (M) were investigated by quantum mechanical calculations at 0 and 298 K. Total energies, zero-point energies scaled by a 0.96 factor, and thermal enthalpy corrections for all optimized structures were computed at the B3-LYP/6-31G(d) level of theory. Differences in enthalpies for elementary propagation reactions at 0 and 298 K did not exceed 0.6 kcal/mol. Enthalpic effects of the replacement of S by M in the penultimate position of the growing radicals in elementary copolymerization propagation reactions (enthalpic penultimate unit effects) were always positive, ranging from 1.2 to 3.3 kcal/mol at 298 K. The values suggested that the elementary propagation reactions involving more S units in the growing polymer chain ends should be slightly thermodynamically preferred. A comparison of these results with those for the S-acrylonitrile monomer system showed that the most crucial feature differentiating enthalpic effects for the two monomer systems is the replacement of M by acrylonitrile in the reaction pair CH 3 -S-M ⅐ ϩ M 3 CH 3 -S-M-M ⅐ and CH 3 -M-M ⅐ ϩ M 3 CH 3 -M-M-M ⅐ .
Iranian Polymer Journal, 2013
The solution copolymerization of methacrylic acid (MAA) and ethyl acrylate (EA) was studied by online proton nuclear magnetic resonance spectroscopy (1 H NMR) using 2,2 0-azobisisobutyronitrile as an initiator in deuterated dimethyl sulfoxide at 60°C. The chemical compositions of the copolymer and the comonomer concentrations were determined from the conversion of comonomers to copolymer by quantitative in situ NMR monitoring to estimate the reactivity ratios of the comonomers at low conversion. This is a new and easy methodology to analyze radical copolymerization. In this research, it is shown that monomer reactivity ratios can be calculated by data collected only from one initial comonomer mixture composition via online monitoring progress of the copolymerization reaction. The reactivity ratios of MAA and EA are equal to 2.360 and 0.414, respectively. This approach is used to compute the monomer reactivity ratios in a nonlinear integrated form of the copolymerization equation which is described by Mayo and Lewis terminal model. The fairly good agreement between the results and the literature data reported for the emulsion system represent the accuracy of the reactivity ratios calculated by this new approach. The calculated reactivity ratios for emulsion copolymerization are r MAA = 2.040 and r EA = 0.470, and the previous literature data are r MAA = 2.580 and r EA = 0.157.