Radical polymerization and copolymerization behavior of 1-cyanoethanoyl-4-acryloylthiosemicarbzide (original) (raw)
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Macromolecular Chemistry and Physics, 1994
Methyl 2-(benzyloxymethyl)acrylate (MBZMA) which was synthesized by reaction of methyl 2-(bromomethy1)acrylate with benzyl alcohol was radically homo-and copolymerized. MBZMA polymerized as fast as methyl methacrylate despite of the presence of a large 2-substituent. The absolute rate constants for propagation and termination were evaluated from the direct determination of the steady state concentration of the propagating radical by electron spin resonance spectroscopy at 60°C: k , = 182 dm3. mol-' * s-' and k, = 1,6. lo6 dm3. mol-' * s-'. It was deduced from the magnitude of the rate constants that the balance of the slow propagation and termination allows the formation of a polymer. Evaluation of the cross-propagation rate constants in the copolymerization with styrene revealed that primarily the steric effect of the benzyloxymethyl group reduced the reactivity of the polymer radical and that the electronwithdrawing character of the 2-substituent prevailing the steric effect enhanced the monomer reactivity toward the polystyrene radical.
Polymer Chemistry, 2013
Propagation rate coefficient (k p ) data for radical polymerization of methyl acrylate (MA) in the bulk are critically evaluated and a benchmark dataset is put forward by a task-group of the IUPAC Subcommittee on Modeling of Polymerization Kinetics and Processes. This dataset comprises previously published results from three laboratories as well as new data from a fourth laboratory. Not only do all these values of k p fulfill the recommended consistency checks for reliability, they are also all in excellent agreement with each other. Data have been obtained employing the technique of pulsed-laser polymerization (PLP) coupled with molar-mass determination by size-exclusion chromatography (SEC), where PLP has been carried out at pulse-repetition rates of up to 500 Hz, enabling reliable k p to be obtained through to 60 C. The best-fitand therefore recommended -Arrhenius parameters are activation energy E A ¼ 17.3 kJ mol À1 and pre-exponential (frequency) factor A ¼ 1.41 Â 10 7 L mol À1 s À1 . These hold for secondary-radical propagation of MA, and may be used to calculate effective propagation rate coefficients for MA in situations where there is a significant population of mid-chain radicals resulting from backbiting, as will be the case at technically relevant temperatures. The benchmark dataset reveals that k p values for MA obtained using PLP in conjunction with MALDI-ToF mass spectrometry are accurate. They also confirm, through comparison with previously obtained benchmark k p values for n-butyl acrylate, methyl methacrylate and n-butyl methacrylate, that there seems to be identical familytype behavior in n-alkyl acrylates as in n-alkyl methacrylates. Specifically, k p for the n-butyl member of each family is about 20% higher than for the corresponding methyl member, an effect that appears to be entropic in origin. Furthermore, each family is characterized by an approximately constant E A , where the value is 5 kJ mol À1 lower for acrylates.
Macromolecular Chemistry and Physics, 2018
Poly(2-ethylhexyl acrylate) was synthesized by conventional radical bulk polymerization both with and without 1-dodecane thiol as chain transfer agent (CTA) at temperatures from 4 to 140 °C. Electrospray-ionization mass spectrometry was used to analyze the polymer. This revealed the occurrence of significant β-scission at high temperature and confirmed the presence of CTA-capped polymers at all temperatures, as well as combination products from 4 to 65 °C. Subsequent 13 C melt-state NMR analysis allowed quantification of branching and β-scission. Both are reduced when CTA is present, consistent with a "patching" effect. As expected, the amounts of β-scission and branching increase with synthesis temperature, although β-scission dominates at the highest temperature. The backbiting rate coefficient of 2-ethylhexyl acrylate was determined from NMR results, taking β-scission into account for the first time. Remarkable agreement with literature k bb values was obtained, especially for activation energy. This strongly suggests family-type behavior for acrylate k bb .
Radical polymerization of methyl trans-β-vinylacrylate
Journal of Polymer Science Part A: Polymer Chemistry, 1995
Methyl trans-P-vinylacrylate (MVA) undergoes radical polymerization with a,a'-azobis(isobutyronitri1e) (AIBN) in bulk and solution. The polymer obtained consists of 85% trans-l,4 and 15% truns-3,4 units. Poly(MVA) (PMVA) is readily soluble in common organic solvents, but insoluble in n-hexane and petroleum ether. PMVA exhibits a glass transition at 6"C, and loses no weight up to 300°C in nitrogen. The kinetics of MVA homopolymerization with AIBN was investigated in benzene. The rate of polymerization (R,) can be expressed by R,, = k[AIBN]o.5[MVA]'.o, and the overall activation energy has been calculated to be 94 kJ/mol. The propagation radical of MVA at 80°C was detected by ESR spectroscopy, which indicated that the unpaired electron of the propagating radical was completely delocalized over the three ally1 carbons. Furthermore, the steady-state concentration of the propagating radical of MVA a t 60°C was determined by ESR spectroscopy, and the propagation rate constant (kp) was calculated to be 1.25 X 10' L/mol.s. Monomer reactivity ratios in copolymerization of MVA (M 2) with styrene (M ,) are r1 = 0.16 and r2 = 4.9, from which Q and e values of MVA are calculated as 4.2 and-0.32, respectively.
Journal of Polymer Science Part A: Polymer Chemistry, 1999
Ethyl-2-(2-cyano-2-ethylthio)-ethyl-propenoate (ECEP) was synthesized and examined as free-radical addition-fragmentation chain transfer agent (AFCTA) in the bulk polymerization of methyl methacrylate (MMA) and styrene at various temperatures. A better chain transfer constant (C tr) was observed for styrene than for MMA, projecting the potentiality of the compound as a better end-functionalizing agent for the former. In both cases, copolymerization of ECEP with the monomer predominated over fragmentation, the relative proportions of which were dependent on the monomer. The ECEP-terminated radical fragmented to an extent of 26% in the presence of MMA, whereas it was only 9.5% in the case of styrene. The relative extent of fragmentation and copolymerization was in conformation to the calculated reactivity ratios and chain transfer constants. Addition-fragmentation chain transfer resulted in the formation of methacrylic-functional macromonomers. The copolymerizability of the resultant macromonomer was found to depend on the nature of the backbone and on the comonomer. On copolymerizing with MMA, the terminal monomer moiety on polystyrene (PS)-based macromonomers preferred to undergo fragmentation, whereas that of the polymethyl methacrylate (PMMA)-based one copolymerized readily with styrene because of thermodynamic and kinetic factors.
The radical polymerization of methacrylic acid, acrylic acid and acrylamide in aqueous solution has been investigated. Detailed kinetic models for both acrylic acid, AA, and methacrylic acid, MAA, have been developed applying the program PREDICI TM. Good representation of experimental conversion vs. time profiles and molar mass distributions as well as, in case of AA, the branching level could be achieved. The polymerization of MAA has been studied at 35 and 50 °C with focus on the influence of 2-mercaptoethanol, ME, as chain transfer agent, CTA, on reaction kinetics. The rate coefficient of transfer to CTA, tr,CTA , k was measured for different monomer levels by the Mayo and the chain length distribution procedure. The ratio of tr,CTA k to the propagation rate coefficient, p k , is independent of monomer to water ratio while both rate coefficients increase by approximately one order of magnitude in passing from bulk to dilute aqueous solution. It was found that addition of CTA reduces the rate of MAA polymerization by two effects on t. k At negligible monomer conversion, t k increases towards higher content of CTA, because average chain length is reduced by the CTA. Chain-length dependent termination may be represented by adopting the composite model, which is a well-established theory to describe chain-length dependency of termination of macroradicals of identical size. The composite model could be applied to average chain length. The reduction of t k towards higher degrees of monomer conversion
Modeling the free radical polymerization of acrylates
International Journal of Quantum Chemistry, 2005
Acrylates have gained importance because of their ease of conversion to high-molecular-weight polymers and their broad industrial use. Methyl methacrylate (MMA) is a well-known monomer for free radical polymerization, but its ␣-methyl substituent restricts the chemical modification of the monomer and therefore the properties of the resulting polymer. The presence of a heteroatom in the methyl group is known to increase the polymerizability of MMA. Methyl ␣-hydroxymethylacrylate (MHMA), methyl ␣-methoxymethylacrylate (MC 1 MA), methyl ␣-acetoxymethylacrylate (MAcMA) show even better conversions to high-molecular-weight polymers than MMA. In contrast, the polymerization rate is known to decrease as the methyl group is replaced by ethyl in ethyl ␣-hydroxymethylacrylate (EHMA) and t-butyl in t-butyl ␣-hydroxymethylacrylate (TBHMA). In this study, quantum mechanical tools (B3LYP/6-31G*) have been used in order to understand the mechanistic behavior of the free radical polymerization reactions of acrylates. The polymerization rates of MMA, MHMA, MC 1 MA, MAcMA, EHMA, TBHMA, MC 1 AN (␣-methoxymethyl acrylonitrile), and MC 1 AA (␣-methoxymethyl acrylic acid) have been evaluated and rationalized. Simple monomers such as allyl alcohol (AA) and allyl chloride (AC) have also been modeled for comparative purposes.
Kinetic study of the radical polymerization behavior ofN-(1-phenylethylaminocarbonyl)methacrylamide
Journal of Polymer Science Part A: Polymer Chemistry, 2005
Polymerization of N-(1-phenylethylaminocarbonyl)methacrylamide (PEACMA) with dimethyl 2,2Ј-azobisisobutyrate (MAIB) was kinetically studied in dimethyl sulfoxide (DMSO). The overall activation energy of the polymerization was estimated to be 84 kJ/mol. The initial polymerization rate (R p) is given by R p ϭ k[MAIB] 0.6 [PEACMA] 0.9 at 60°C, being similar to that of the conventional radical polymerization. The polymerization system involved electron spin resonance (ESR) spectroscopically observable propagating poly(PEACMA) radical under the actual polymerization conditions. ESRdetermined rate constants of propagation and termination were 140 L/mol s and 3.4 ϫ 10 4 L/mol s at 60°C, respectively. The addition of LiCl accelerated the polymerization in N,N-dimethylformamide but did not in DMSO. The copolymerization of PEAC-MA(M 1) and styrene(M 2) with MAIB in DMSO at 60°C gave the following copolymerization parameters; r 1 ϭ 0.20, r 2 ϭ 0.51, Q 1 ϭ 0.59, and e 1 ϭ ϩ0.70.