Acidolytic polymerization of N-methyldodecanelactam

The polymerization rate of 1-methylazacyclotridecan-2-one (N-methyldodecanelactam) ( 1 ) initiated with dodecanoic acid ( 2 ) can be described within the whole range of conversions in terms of the simple relation In ([ 1 ]₀/[ 1 ]) = k[ 2 ]₀t, in spite of the complexity of the overall reaction scheme. The rate constants (k) determined for 240, 260, and 280°C are 0,32, 1,21, and 3,4 kg · mol^?1 h^?1, respectively, and the constants of the Arrhenius equation are A = 6,6 · 10¹³kg · mol^?1 h^?1, E = 140 kJ · mol^?1. The resulting poly(N-methyldodecaneamide) ( 3 ) is a semicrystalline polymer (m.p. 65°C), soluble in polar organic solvents. The following constants of the Mark-Houwink equation were determined for solutions of this polyamide: for 5000 < M?_w < 150 000 g · mol^?1 at 25°C in THF (2-propanol), K = 0,124 (0,161) cm³ · g^?1, a = 0,59 (0,56); for 5 000 < M?_w < 80 000 g · mol^?1 at ?-temperature = 30,5°C in 1,4-dioxane, K = 0,215 cm³ · g^?1, a = 0,50. Analyses of molar masses, both theoretical and experimental (light-scattering, GPC, osmometry, end groups), indicate that at the polymerization temperature of 280°C side reactions already take place, reflected in random cleavage and in branching of chains.     

Kinetic and ESR studies of the radical-initiated polymerization of N-(2,6-dimethylphenyl)itaconimide

The polymerization of N-(2,6-dimethylphenyl)itaconimide (1) with azoisobutyronitrile (2) was studied in tetrahydrofuran (THF) kinetically and spectroscopically with the electron spin resonance (ESR) method. The polymerization rate (R_p) at 50°C is given by the equation: R_p = K [2] ^0,5 · [1] ^2,1. The overall activation energy of the polymerization was calculated to be 91 kJ/mol. The number-average molecular weight of poly (1) was in the range of 3500–6500. From an ESR study, the polymerization system was found to involve ESR-observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (k_p) and termination (k_t) were determined at 50°C. k_p (24–27 L · mol^?1 · s^?1) is almost independent of monomer concentration. On the other hand, k_t (3,8 · 10⁴–2,0 · 10⁵ L · mol^?1 · s^?1) increases with decreasing monomer concentration, which seems mainly responsible for the high dependence of R_p on monomer concentration. Thermogravimetric results showed that thermal degradation of poly (1) occurs rapidly at temperatures higher than 360°C and the residue at 500°C was 12% of the initial polymer. For the copolymerization of 1 (M₁) with styrene (M₂) at 50°C in THF the following copolymerization parameters were found; r₁ = 0,29, r₂ = 0,08, Q₁ = 2,6, and e₁ = +1,1.     

Effect of SnCl4 on the radical-initiated polymerization of diethyl itaconate: Kinetical and ESR studies

The effect of SnCl₄ on the polymerization of diethyl itaconate ( 1 ) with dimethyl 2,2′-azoisobutyrate ( 2 ) in benzene was investigated kinetically and ESR spectroscopically. The polymerization rate (R_p) at 50°C shows a flat maximum on varying the SnCl₄ concentration. The molecular weight of the resulting polymer decreases with increasing SnCl₄ concentration. The overall activation energy of the polymerization is lowered from 52 to 33 kJ · mol^?1 by the presence of SnCl₄, (0,342 mol · L^?1). An NMR study revealed that 1 and SnCl₄ form 1:1 and 2:1 complexes with a large stability constant in benzene. The propagating polymer radicals in the absence and presence of SnCl₄ are ESR-observable as a five-line spectrum under the actual polymerization conditions. The complexed polymer radicals show further three-line splitting due to two methylene hydrogens of the ethyl ester group. The polymer radical concentration increases with the SnCl₄ concentration. The rate constant (k_p) of propagation was determined using R_p and the polymer radical concentration. k_p (6,3–2,9 L · mol^?1 · s^?1 at 50°C) decreases with increasing SnCl₄ concentration. The presence of SnCl₄ (0,342 mol · L^?1) reduces the activation energy of propagation from 29 to 21 kJ · mol^?1. The rate constant (k_t) of termination was estimated from the decay curve of the polymer radicals, k_t (3,1–1,1 · 10⁵ L · mol^?1 s^?1) also decreases with the SnCl₄ concentration. The activation energies of termination in the absence and presence of SnCl₄ (0,342 mol · L^?1) are 30 and 24 kJ · mol^?1, respectively. Suppression of propagation and termination by SnCl₄ seems to be explicable in terms of an entropy factor.     

Poly{[(Chloro-2 éathyl)-4 phéanyl]-1 éathylène}: Synthèse,caractérisations,dégradation thermique et modifications chimiques

Poly{1-[4-(2-chloroethyl)phenyl]ethylene} ( 3 ) was synthesized by bulk polymerization of 4-(2-chloroethyl)styrene ( 6 ) in two steps from commercial products. The polymer was characterized by means of GPC (weight-average molecular weight M?_w = 85 000 and number-average molecular weight M?_n = 63 500), ¹H NMR and ¹³C NMR spectroscopy. The first stage of thermal degradation begins at 290°C and ends at about 410°C. The overall activation energy was calculated to be 43 kcal · mol^?1 (180 kJ · mol^?1). The solid residue was crosslinked and insoluble. The volatile products, identified by gas chromatography-mass spectroscopy (GC-MS), were chiefly hydrogen chloride, dichloromethane and monomer. In a strongly basic medium, nucleophilic substitution of chlorine was achieved without elimination.     

Polymerization of 2,2-dimethyltrimethylene carbonate with tri-sec-butoxyaluminium; a kinetic study

The polymerization of 2,2-dimethyltrimethylene carbonate (DTC, 1 ) with tri-sec-butoxyaluminium (Al(O-sec-Bu)₃) proceeds with suppression of macrocyclics formation. The propagation of the polymerization proceeds pseudoanionically via insertion. Within the scope of a kinetic treatment, the time-conversion relationship was determined for the polymerization of DTC with Al(O-sec-Bu)₃ as initiator and toluene as solvent. For a polymerization temperature between 15°C and 74°C, the apparent rate constant was found to be between 0,1 and 1,0 L · mol^?1 · s^?1. Using the Arrhenius plot the experimental temperature coefficient (20,6 kJ · mol^?1) as well as the frequency factor of the polymerization (1,3 · 10³ L · mol^?1 · s^?1) were determined. Investigation of the dependence of the rate of polymerization on the initiator concentration revealed a degree of aggregation of 2 for the active species.     

Aqueous polymerization of acrylamide initiated by acidic permanganate/thiourea redox system

The polymerization of acrylamide, initiated by acidic permanganate/thiourea redox system, was studied in aqueous media at 30 ± 0,2 °C in nitrogen. The rate of polymerization (R_p) was found to be proportional to nearly the first power of the catalyst (KMnO₄) concentration, within the range of 0,5 · 10^?2 to 1,4 · 10^?2 mol dm^?3, and independent of the thiourea concentration. However, the rate of polymerization varies with the first power of the hydrochloric acid concentration within the range of 2,85 · 10^?2 to 11,4 · 10^?2 mol dm^?3, and increases linearly up to certain extent by varying the monomer concentration from 2,5 · 10^?2 to 12,5 · 10^?2 mol dm^?3. A deviation from the linear behaviour is observed, however, above a concentration of 12,5 · 10^?2 mol dm^?3. The initial rate of polymerization (R_i) as well as the maximum conversion increases by increasing the temperature up to 35 °C, but the maximum conversion falls as the temperature rises above 35 °C. The overall energy of activation is found to be 47,70 kJ mol^?1 (11,48 kcal/mol^?1) within the temperature range of 25–45 °C. Addition of salts, except manganous salts, was found to be associated with a depression in the R_p and maximum conversion. The effect of cationic and anionic surfactants has been found to increase and decrease the R_p respectively; non-ionic detergents, however, have no effect on the R_p.     

Solvent effect on the propagation rate constant in the radical polymerization of bis(2-ethylhexyl) itaconate

Polymerization of bis(2-ethylhexyl) itaconate ( 1 ) with dimethyl azobis(isobutyrate) ( 2 ) was carried out at 50°C in various solvents. Polar solvents caused a significant decrease in the polymerization rate (R_p) and the molecular weight of resulting poly( 1 ). The propagating poly( 1 ) radical could be observed as a five-line ESR spectrum in the actual polymerization systems used. The stationary concentration of poly( 1 ) radical was determined by ESR to be 4,2–6,4 · 10^?6 mol · L^?1 at 50°C when the concentrations of 1 and 2 were 1,03 and 3,00 · 10^?2 mol · L^?1. Using R_p the monomer concentration and the polymer radical concentration, the propagation rate constant (K_p) was estimated to be 1,4–6,8 L · mol^?1 · s^?1, depending on the solvents used. The k_p value was smaller in more polar solvents. The solvent effect is explained in terms of the solvent affinity for the propagating polymer chain.     

4-(α,α-dimethylbenzyl)phenyl methacrylate, 2. Polymerization in N,N-dimethylformamide

The polymerization rate of 4-(α,α-dimethylbenzyl)phenyl methacrylate in DMF at 70°C is of the order 1,6 in [monomer] and first order in [AIBN], which deviates from classical kinetics. This could be reconciled by a reaction scheme in which dimeric monomer associates and a spontaneous termination are postulated. The scheme is supported by the dependence of the kinetic chain length, v, on the 1,6-th power in [monomer] and zeroth power in [AIBN]. The degree of polymerization is smaller than v, which indicates some chain transfer. A remarkable feature is the constancy of the dispersion degree, M?_w/M?_n, of the polymers of about 1,4 up to high degrees of conversion. The overall activation energy of the polymerization, E_a, is 60,1 kJ · mol^?1, and the preexponential factor ln A ≈ 15,5 (A in (mol · dm^?3)^?1,5 · s^?1). The polymer chains seem to have a rod-like character in THF as deduced from the Mark-Houwink exponent of 1,46. In toluene the polymer tends to form associates.     

The initiation of polymerization of unsaturated tertiary amines with carboxylic acids

The polymerization rate (R_p) of N-methyl-N-phenyl-2-aminoethyl methacrylate (MPAEMA) initiated with 2,2' -azodiisobutyronitrile (AIBN) at 50°C increased considerably after the addition of CCI₃COOH, and distinctly after the addition of CH₃COOH. R_p in a benzene solution of 2 mol. dm^?3 MPAEMA and 5 · 10^?2 mol. dm^?3 CCl₃COOH (without AIBN) was 13% · h^?1. [η] of the obtained polymer corresponded to 64 cm³ · g^?1. The polymerization order of MPAEMA initiated with CCl₃COOH is 0,93 with respect to monomer and 0,51 with respect to CCl₃COOH. The overall activation energy of polymerization of MPAEMA calculated from the temperature dependence of R_p between 20 and 50°C is 43 ± 1,2 kJ · mol^?1. In a benzene solution of 2 mol.dm^?3 MPAEMA, 5 · 10^?2 mol · dm^?3CCl₃COOH and 5 · 10^?3 mol · dm^?3 1,4-benzoquinone at 50°C the polymerization does not proceed for 6 h. In a benzene solution of 2 mol · dm^?3 4-dimethylaminostyrene (4-DMAS) and 2 mol · dm^?3 CH₃COOH (without AIBN), 40% of monomer polymerized within one hour. [η] of the polymer was 4 cm³ · g^?1. The overall activation energy of polymerization of 4-DMAS in the presence of CH₃COOH is ca · 54 kJ · mol^?1. The addition of 5 · 10^?3 1,4-benzoquinone slows down the polymerization rate only slightly. The effect of acids on the elementary polymerization reactions is characterized.     

The polymerization of isobutyl vinyl ether by trifluoroacetic acid

The polymerization of isobutyl vinyl ether (IBVE) initiated by trifluoroacetic acid (TFA) in 1,2-dichloroethane and in 1,2-dichloroethane/carbon tetrachloride mixtures has been studied over the temperature range ?2,5°C to 35°C. Provided that the ratio [IBVE]/[TFA] did not exceed 88 and that 2·10^?4 mol·1^?1 < [TFA] < 4·10^?3 mol·1^?1 polymerization was the only detectable reaction, and the initial rate of reaction R₀ was equal to k[IBVE]²[TFA]. The activation energy of the rate = (34 ± 2) kJ · mol^?1 and the activation energy of the molecular weight = ? (11,9 ± 0,5) kJ · mol^?1. When [TFA] < 1·10^?4 mol/l, no reaction was detectable. The polymers produced had molecular weights less than 4400; the only transfer is by monomer and this is the main chain-breaking step. The reaction was unaffected by the addition of water for [H₂O] < [TFA]. The rate depended on the solvent dielectric constant, but in a manner suggestive of a dipole-dipole reaction. A mechanism is proposed for the reaction in which the reactive intermediates are trifluoroacetate esters solvated by monomer.     

Elementary reactions in the cationic polymerization of oxepane. Comparison with the polymerization of tetrahydromfuran

In the polymerization of oxepane (OXP), initiated with derivatives of trifluoromethanesulfonic acid, covalent and ionic active centers were simultaneously observed by ¹H and ¹⁹F NMR spectroscopy. A higher proportion of secondary oxonium ions (these species detected by ¹⁹F NMR were independently observed by proton trapping with R₃P in the ³¹P NMR spectrum). The proportion of ionic species decreases with monomer conversion, indicating a substantial contribution of bimolecular ionization of the monomer. The effective molarity in oxepane polymerization [OXP]_eff ? 1 mol ·I^-1 was found to be lower by a factor of 10² than [THF]_eff in the polymerization of THF. The rate constant of the covalent propagation in the polymerization of OXP is similar to that measured for THF, however, due to the reduced reactivity of the oxepanium cation, the relative reactivity of the covalent active centers becomes higher than that of the ions. Thus, for OXP, in CH₃NO₂ at 25°C, K_pc = 3 · 10^?4 mol^?1 · 1 · s^?1, k_pi = 2 · 10^?4 mol^?1 · 1 · s^?1 whereas for THF k_pc = 5 · 10^?4 mol^?1 · 1 · s^?1 and k_pi = 2 · 10^?2 mol^?1 · 1 · s^?1 under similar conditions. The rates of ionization and temporary termination, measured by the “temperature jump” technique, allow to determine the contributions of inter-and intramolecular ionizations. These rates becomes equal at [OXP] = 1 mol · 1^-1 (= [OXP]_eff).     

Polymerization of lactams, 54. Anionic polymerization of 2-pyrrolidone accelerated with CO2, part 3

Intrinsic viscosities in m-cresol and weight average molecular weights, M?_w, were measured for samples of high molecular weight poly(2-pyrrolidone) (poly ( 1 )) prepared by anionic polymerization of 2-pyrrolidone ( 1 ) accelerated with CO₂. It was proved that the earlier found relationship [η] = 4 · 10^?2 · M^0,77 (in cm³ · g^?1) holds for M?M_w up to 8 · 10⁵ g. mol^?1. The probable reason for the formation of poly ( 1 ) with an exceptionally high molecular weight is discussed.     

Thermodynamics of copolymerization of 1,3-dioxolane with 1,3-dioxepane and 1,3-dioxane

The equilibrium copolymerization of 1,3-dioxolane with 1,3-dioxepane in CH₂Cl₂ solution and with 1,3-dioxane without solvent is analyzed, and the equilibrium constants of homo- and cross-propagations are estimated and discussed. The corresponding thermodynamic parameters are calculated. The reported thermodynamic parameters of homopolymerization of 1,3-dioxane (ΔH_ss = ?3,1 kJ · mol^?1, ΔS_ss = ?35,5 J · mol^?1 · K^?1), were determined on the basis of the copolymerization data. Predictions of comonomer concentrations and microstructure of copolymers in the equilibrium copolymerization system are presented for any initial composition, on the basis of the determined equilibrium constants.     

Zwitterionic polymerization of butyl cyanoacrylate by triphenylphosphine and pyridine

This paper describes a re-examination of the kinetics and molecular weights formed in the zwitterionic polymerization of butyl cyanoacrylate by triphenylphosphine (Ph₃P) and pyridine (Py) in THF, and an extension to include the solvents, diethyl ether (Et₂O), dimethoxyethane (DME) and hexane. In THF, the previously observed kinetics were confirmed, yielding evidence for absence of termination, and values for rate constants for initiation (k_i) and propagation (k_p) with substantial agreement between the values for K_p obtained from both systems. At 20°C, the mean value found for k_p in THF was 3 · 10⁵ l · mol^?1 · s^?1; in Et₂O, some 10 times lower, and in hexane, 10 times lower again. The temperature dependence of k_p in THF was confirmed to be extremely low and anomalous; in Et₂O rather greater and near-normal, corresponding to an energy of activation of ca. 5 kcal · mol^?1. A correction procedure enabled the large experimental scatter in the k_p values to be reduced sufficiently to reveal trends downwards at higher concentrations of propagating species, i.e. evidence for their dissociation on dilution. In Py-initiated polymerizations, excess of pyridinium salts did not depress k_p; evidence that the propagating species are preponderately paired ions, not free. It is concluded that at 20°C these species are mainly ‘tight’ ion-pairs in all solvents, and remain so in Et₂O at all temperatures down to ?80°C. In THF, over this temperature range, there is increasing solvation producing an increasing proportion of more reactive ‘solvent-separated’ ion-pairs. The molecular weights produced under all conditions were high (M _n usually 1 to 3 · 10⁶). Those produced by high concentration of Ph₃P did not conform to theory; others followed the ‘no-termination’ theory as modified to allow for a small effect of transfer.     

Anionic polymerization of one-ended “living” strontium-polystyrene in tetrahydropyran in the presence of tetraglyme and in benzene

The anionic polymerization of the strontium salt of one-ended living polystyrene (SrS₂) was investigated at 20°C in tetrahydropyran (THP) in the presence of two different concentrations of added tetraglyme. Similarly to BaS₂ in tetrahydrofuran (THF) and to SrS₂ in THF and in pure THP, the observed pseudo-first-order rate constant of propagation, k_obs, was nearly independent of the total concentration of salt, their values being 7,5.10^?3 s^?1 and 9 · 10^?3 s^?1, respectively, i. e. about 100 to 120 times higher than in pure THP. This indicates that the propagation occurs mainly via an increased but constant amount of free S^? anions resulting from the two already known equilibria SrS₂ ? (SrS)⁺ + S^?(K₁) and 2 SrS₂ ? (SrS)⁺ + (SrS₃)^? (K₂) and the equilibrium of glymation (SrS⁺) + G ? G, (SrS)⁺ (K_i). A small not exactly determinable contribution of glymated ion-pairs and/or triple ions, whose rate constants would then probably be of the order of 18 l · mol^?1 · s^?1 and 80 l · mol^?1 · s^?1, respectively, could not be excluded. The glymation constant K_i was found to be about 3 · 10⁶ 1 · mol^?1, i.e., approximately 17 times greater than for the Na⁺ cation. Finally, a kinetic experiment with SrS₂ at 20°C in pure benzene (contaminated, however, with some remaining THP from the preparation of SrS₂) indicated that propagation by ion-pairs is possible with a bimolecular apparent rate constant K_app = 1,1 · 10^?1 l · mol^?1 · s^?1.     

Polymeric peroxycarbamates: Synthesis,characterization and their initiation of styrene polymerization

Three different polymeric peroxycarbamates were synthesized using polyether glycols, a cycloaliphatic diisocyanate and a dihydroperoxide. The products were characterized by infrared spectroscopy, molecular weight measurements and isocyanate and peroxygen analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in toluene or 1,4-dioxane solutions at 80, 90 and 100°C. All reactions were found to proceed according to the first-order kinetics with activation energies in the range of 123 to 145 kJ · mol^?1, depending on the structure of the peroxycarbamate. One of the products was used to initiate styrene polymerization at 80°C, in bulk. The initiating activity of this polymeric peroxycarbamate was found to be better than that of some hydroperoxides.     

Electric dipole moment of ethylcellulose,in 1,4-dioxane and in benzene

The electric dipole moments per repeating unit of ethylcellulose (EC) of various molecular weights were determined by dielectric measurements at 1 kHz (μ_L) and at 1 MHz (apparent moment, μ_H) in 1,4-dioxane and benzene. The numerical values were μ_L = 5,23 D (= 17,45.10^?30 C·m) and μ_H + 2,72 D (= 9,07.10^?30 C·m) for 1,4-dioxane, and μ_L = 4,81 D (= 16,04.10^?30 C·m) and μ_H = 2,42 D (= 8,07.10^?30 C·m) for benzene, respectively. μ_L and μ_H were almost independent of the molecular weight in both solutions. The persistence dipole moment μ_q was estimated to be 13,6 D (= 45,36.10^?30 C·m) in 1,4-dioxane, and 13,4 D (= 44,70.10^?30 C·m) in benzene, respectively, and the flexibility of the EC chain was discussed.     

Kinetic and ESR studies on radical polymerization. Radical polymerization behavior of N-octadecylmaleimide in benzene

The polymerization of N-octadecylmaleimide ( 1 ) initiated with azodiisobutyronitrile ( 2 ) was investigated kinetically in benzene. The overall activation energy of the polymerization was calculated to be 94,2 kJ·mol^?1. The polymerization rate (R_p) at 50°C is expressed by the equation, R_p = k[ 2 ]^0,6[ 1 ]^1,7. The homogeneous polymerization system involves ESR-detectable propagating polymer radicals. Using R_p and the polymer radical concentration determined by ESR, the rate constants of propagation (k_p) and termination (k_t) were evaluated at 50°C. k_p (33 L · mol^?1 · s^?1 on the average) is substantially independent of the monomer concentration. On the other hand, k_t (0,3 · 10⁴ – 1,0 · 10⁴ L · mol^?1 · s^?1) is fairly dependent on the monomer concentration, which is ascribable to a high dependence of k_t on the chain length of rigid poly( 1 ). This is the predominant factor for the high order with respect to the monomer concentration in the rate equation. In the copolymerization of 1 (M₁) and St (M₂) with 2 in benzene at 50°C, the following copolymerization parameters were obtained: r₁ = 0,11, r₂ = 0,09, Q₁ = 2,1, and e₁ = +1,4.     

Study of the mechanism of propagation and transfer reactions in the polymerization of olefins by Ziegler-Natta catalysts, 2. The influence of polymerization temperature on the kinetic characteristics of propagation

By quenching polymerization with radioactive carbon monoxide (¹⁴CO) data on the number of propagation centers (C_p) and the propagation rate constant (K_p) were obtained for the ethylene and propene polymerization in the presence of titanium trichloride at different temperatures. The values of K_p for ethylene and propene polymerization were found to be 8,0·10⁵ e^?13/(RT) and 3,0·10⁵ e^?23/(RT) l mol^?1 S^?1, respectively (activation energies in kJ mol^?1). It was further found that at increasing polymerization temperature the steady-state concentration of propagation centers increased when using Al(C₂H₅)₃ and Al(C₂H₅)₂Cl as cocatalysts, whereas it did practically not change in the case of Al(isobutyl)₃. On the basis of these data several conclusions were drawn on the mechanism of propagation and the role of organoaluminium cocatalysts in this reaction.