Regularities of the kinetics of miniemulsion polymerization of styrene in the presence of dithiobenzoates as reversible chain transfer agents (original) (raw)
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Comptes Rendus Chimie, 2003
The radical polymerization of styrene was investigated in the presence of diphenyl ditelluride (DPDTe) under varied conditions. In the polymerization without any radical initiator at higher temperature (125°C), the addition of DPDTe surely decreased the polymer molecular weight (M n ) while the polydispersity (M w /M n ) was rather broad. The polymerization with benzoyl peroxide (BPO) as the initiator was also uncontrollable to afford polymers with broad M w /M n probably due to the redox side reaction of BPO with DPDTe. On the contrary, the precision control of M n and the initiating end structure could be achieved by the polymerization with 2,2'azobisisobutyronitrile (AIBN), that is, M n increased in proportion to the molar ratio of monomer to initiator suggesting the suppression of bimolecular chain termination reactions by the excellent radical capturing ability of DPDTe.
Macromolecules, 2007
The radical polymerization of styrene was investigated in the presence of diphenyl ditelluride (DPDTe) under varied conditions. In the polymerization without any radical initiator at higher temperature (125°C), the addition of DPDTe surely decreased the polymer molecular weight (M n ) while the polydispersity (M w /M n ) was rather broad. The polymerization with benzoyl peroxide (BPO) as the initiator was also uncontrollable to afford polymers with broad M w /M n probably due to the redox side reaction of BPO with DPDTe. On the contrary, the precision control of M n and the initiating end structure could be achieved by the polymerization with 2,2'azobisisobutyronitrile (AIBN), that is, M n increased in proportion to the molar ratio of monomer to initiator suggesting the suppression of bimolecular chain termination reactions by the excellent radical capturing ability of DPDTe.
Macromolecular Reaction Engineering, 2009
Calculations of polymerization kinetics and molecular weight development in the dithiolactone-mediated polymerization of styrene at 60 8C, using 2,2 0-azobisisobutyronitrile (AIBN) as initiator and g-phenyl-g-butirodithiolactone (DTL1) as controller, are presented. The calculations were based on a polymerization mechanism based on the persistent radical effect, considering reverse addition only, implemented in the PREDICI 1 commercial software. Kinetic rate constants for the reverse addition step were estimated. The equilibrium constant (K ¼ k add /k-add) fell into the range of 10 5-10 6 L Á mol À1. Fairly good agreement between model calculations and experimental data was obtained.
Effects of chain transfer agent on the radical polymerization of styrene in non-aqueous dispersion
2003
Radical polymerization of styrene was carried out in a homogeneous non-aqueous dispersion media consisting of 95% ethanol in the ethanol-water mixture. Various proportions of carbon tetrabromide were added as a chain transfer agent before polymerizations, carried out under similar conditions. The effects of the chain transfer agent on the percentage conversion, particle size distribution, and molecular weight were measured. The findings show a considerable effect of the chain transfer agent on radical polymerization in non-aqueous dispersion.
Kinetic Studies on Bulk Atom Transfer Radical Polymerization of Styrene
American Journal of Polymer Science and Technology, 2017
The long chain vinyl end-functional polystyrene has been synthesized in bulk polymerization method using atom transfer radical polymerization (ATRP) with Undecenyl-2-Bromopropionate (UnBP) and CuCl/bypyridine catalytic system. The polymerizations demonstrate an increase in molecular weight and conversion in direct proportion to the polymerization time by consumed monomer which exhibited first-order kinetics. This study concludes the simple kinetics of polystyrene synthesized by ATRP using initiator and ligand-to-copper(I) halide was found to be 1:2:1, which tentatively indicates that the coordination sphere of the active copper(I) center contains two bipyridine ligands. The propagation rate has been investigated for long range of time for ensuring that the rate of radical combination or disproportionation is sufficiently less.
Polymer, 2008
The control/livingness in nitroxide-mediated polymerization of styrene (S) in aqueous miniemulsion at 125 C employing a poly(S)-2,2,6,6-tetramethylpiperidinyl-1-oxy (PS-TEMPO) macroinitiator and the surfactant sodium dodecylbenzenesulfonate has been shown to depend strongly on the macroinitiator concentration for particles of approximate number-average diameter 65 nm. The control/livingness was relatively poor at [PS-TEMPO] 0 0.02 M due to the combined effect of enhanced spontaneous initiation and the interface effect (whereby deactivation is suppressed due to interfacial activity of TEMPO). Satisfactory control/livingness was obtained at higher [PS-TEMPO] 0 as a result of the interface effect and enhanced spontaneous initiation exerting less pronounced influence per chain than at lower [PS-TEMPO] 0. Polymerizations using the sulfonate surfactant DOWFAX 8390 gave similar results, indicating that the present macroinitiator concentration effects are not specific to SDBS-based systems. The results also demonstrate that TEMPO-mediated polymerization of S in miniemulsion can proceed at a higher rate than in bulk with good control/livingness.
Radical Polymerization of Styrene in the Presence of Ylide
Polymer Journal, 1985
The effects of fl-picolinium p-chlorophenacylide on the solution polymerization of styrene initiated by rx,rx'-azobisisobutyronitrile (AIBN), using tetrahydrofuran (THF) as an inert solvent, were investigated at 60, 65, and 70°C. Normal kinetic features (Rpoc[AIBN] 0 • 5 [styrene]L 0) were observed for the AIBN initiated polymerization in the absence ofylide but in presence ofylide, the R" was proportional to [AIBN] 0 • 33 [ylide] 0 • 14 [styrene] 0 • 5-1.o The rate of polymerization (R") and average degree of polymerization (P.) increased with increasing [ylide]. The energy of activation decreased in presence of ylide. The effects of polar and non polar solvents were also studied. The accelerating effect ofylide was due to the decrease in the rate of termination (R,
Radical polymerization of styrene initiated by poly(ethylene oxide) macroinitiators
European Polymer Journal, 1992
The kinetics of the polymerization of styrene in bulk and in dilute systems in the presence of p-acetyi benzylidene triphenylarsonium ylide (p-ABTAY) as radical initiator has been examined at 60+0.1°C for 20 h under N2. The values of the initiator exponent and the monomer exponent showed that the system follows ideal radical kinetics with bimolecular termination. The overall activation energy and average value of k~/k t are 64.6 kJ moi -1 and 0.10 × 10-21 mol -1 s -1, respectively. The ylide dissociates to produce phenyl radical, which brings about polymerization.