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.     

Kinetics of the nitrogen dioxide initiated polymerization of acrylic acid

Acrylic acid (AA) was polymerized with NO₂ in tetrahydrofuran (THF) and in 1,4-dioxane. The effects of monomer and initiator concentration and of temperature on polymer conversion, initial rate of polymerization, and molecular weight were studied. The overall activation energy of polymerization was found to be 16,3 kcal mol^?1 (68,23 kJ · mol^?1) and 15,54 kcal · mol^?1 (65,05 kJ · mol^?1) in THF and in 1,4-dioxane, respectively. High molecular weight polymers (M ca. 10⁵) were obtained. The polymerization appears to be initiated by free radicals.     

Anionic polymerization of β-nitrostyrenes

The rate of polymerization of β-nitrostyrene initiated by sodium alkoxide was setudied gravimetrically. The rate was found to be first order with respect to monomer concentration and first order with respect to initiator concentration. Rate constants in the order of 0,25 dm³ · mol^?1 · s^?1 were obtained at 15°C, 20°C, and 25°C for the polymerization of β-nitrostyrene, p-methoxy-β-nitrostyrene, and p-methyl-β-nitrostyrene initiated by sodium methoxide and by sodium ethoxide. The activation energy of polymerizations initiated by sodium methoxide and by sodium ethoxide was ～24 kJ · mol^?1 and ～ 16 kJ · mol^?1, respectively. The number average degree of polymerization of poly(β-nitrostyrene)s was determined by polymerization of the monomer in the pressence of ¹⁴C-alkanol. This is the first time that accurate number average molar masses of poly(β-nitrostyrene)s have been reported since conventional methods of molar mass determination cannot be used owing to the insolubility of these polymers in most common organic solvents.     

Copolymerization of styrene with α-chloromaleic anhydride, 2. Spontaneous copolymerization in 1,4-dioxane

α-Chloromaleic anhydride (CMA) copolymerizes spontaneously with styrene (ST) at a higher rate than maleic anhydride (MA), and α,α′ -dichloromaleic anhydride (DCMA) does not copolymerize, even in the presence of a radical initiator. The results obtained from the copolymerization of ST with CMA in 1,4-dioxane in the absence of a radical initiator are as follows: the copolymerization is strongly accelerated by UV-irradiation; the monomer reactivity ratios of ST and CMA at 60°C are 0,06 and 0,00, respectively; the over-all activation energy of the copolymerization is 77,4 kJ · mol^?1 (18,5 kcal · mol^?1); the maximum rate of copolymerization at a constant total monomer concentration is observed at a mole fraction of ST of 0,4 to 0,5. The rate of copolymerization at equimolar feed composition is of second order with respect to the total monomer concentration. From the results obtained here and shown in the preceding paper, it was inferred that initiating radicals for the spontaneous copolymerization are formed through a charge transfer (CT) complex between the comonomers.     

On the interaction of styrene-maleic anhydride copolymer with styrene

The interaction between alternating styrene/maleic anhydride copolymer as polymeric acceptor and styrene as low molecular weight donor in acetone and/or tetrahydrofuran was investigated by UV spectroscopy and polymerization technique. The equilibrium constant for the complex formation between styrene and the maleic anhydride structural unit of the styrene/maleic anhydride copolymer at 20°C was found to be 0,02 ± 0,001 dm³·mol^?1 in acetone and 0,06 ± 0,003 dm³·mol^?1 in tetrahydrofuran. The results of the thermally initiated polymerization of styrene in acetone in the presence of the alternating styrene/maleic anhydride copolymer indicate that the copolymer or the products of the interaction between the monomeric units of maleic anhydride in the copolymer and styrene do not initiate a radical polymerization of styrene.     

Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride

Ammonium salt catalyzed copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride was studied. The conversion curves could be linearized by the first order equation and the experimental rate constants k_exp for the initiation by various ammonium salts were determined. The rate of copolymerization was found to depend on the size of the cation but not on the type of anion. k_exp is a function of the first power initiator concentration but is independent of epoxide and anhydride concentration. The activation energy for the cetyltrimethylammonium bromide (CAB) initiated copolymerization in nitrobenzene was determined to be 73,5 kJ/mol. The kinetic scheme of copolymerization, which agrees well with the experimental results, was solved. The rate constant of the copolymerization of 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone with phthalic anhydride catalyzed by CAB in nitrobenzene was found to be 2,76·10^?2l.mol^?1·s^?1. The ratio of rate constants for both propagation steps, i.e. reaction of carboxylate anion with epoxide (k₃) and reaction of alkoxide anion with anhydride (k₂), was determined to be k₃/k₂ = 0,2 ± 0,1.     

Styrene polymerization induced by anilino radicals

The polymerization of styrene (St) initiated by 1,4-dimethyl-1,4-diphenyl-2-tetrazene ( 1c ) is studied kinetically in benzene. The polymerization proceeds through a radical mechanism. The rate equation is as follows: R_p = k [ 1c ]^0,5[St]^1,0. The overall activation energy for the polymerization of St is found to be 105,9 kJ · mol^?1. The efficiency of the initiator is also calculated to be 0,67. On the basis of the results, the initiating ability of N-methylanilino radicals is discussed.     

Aqueous polymerization of vinyl monomers in the presence of surfactants, 3. System: Acrylamide/poly(butyl acrylate) latex

The kinetics of the polymerization of acrylamide initiated by potassium peroxodisulfate in aqueous medium is studied in the presence of poly(butyl acrylate) latex. The rate of acrylamide polymerization increases with the concentration of the latex in the reaction system. The increase is especially pronounced at concentrations of solid latex higher than 100 g per dm³ of polymerization mixture. The activation energy of the acrylamide polymerization in the presence of poly(butyl acrylate) latex is 85,8 kJ · mol^?1. This value is substantially higher than the value of 70,7 kJ · mol^?1 found for the activation energy of the polymerization of acrylamide in the absence of poly(butyl acrylate) latex. A set of reactions is proposed and the equation describing the simultaneous homopolymerization of acrylamide and grafting of poly(butyl acrylate) latex with acrylamide is derived.     

Postirradiation polymerization and ESR studies of γ-irradiated N-tert-butylacrylamide

Postirradiation polymerization of γ-irradiated N-tert-butylacrylamide was studied at 80, 85, 90, and 100°C, and the activation energy was found to be 183 kJ · mol^?1. By ESR spectroscopy, the half-life for the second order decay of the irradiated monomer was found to be 13,8 h at 25°C with a decay rate constant of 4,5 · 10⁶ g · mol^?1 · h^?1. The effect of oxygen and sulfur dioxide on γ-irradiated N-tert-butylacrylamide was also studied. It was observed that oxygen reacts with N-tert-butylacrylamide free radicals resulting in a characteristic peroxyl radical spectrum. The signal decays rapidly and disappears in about 100 h. The decay was found to be of second order with a rate constant of 1,3 · 10⁷ g · mol^?1 · h^?1 and a half-life of 3,8 h at 25°C. In contrast to the situation with atmospheric oxygen, an appreciable fraction of the free radicals does not react rapidly with sulfur dioxide. The changes in the ESR spectra indicate that at least a large fraction of the original N-tert-butylacrylamide radicals, generated in the irradiated sample, react with sulfur dioxide rapidly to give sulfonyl radicals. Their decay is second order with a rate constant of 4,5 · 10⁶ g · mol^?1 · h^?1 and a half-life of 8,3 h.     

Aqueous polymerization of vinyl monomers in the presence of surfactants, 2. Methacrylamide

The kinetics of the polymerization of methacrylamide initiated by potassium peroxodisulfate in water and 2,2′-azoisobutyronitrile (AIBN) in a water/ethanol mixture (mass ratio 9/1) were studied in the presence of the emulsifier sodium dodecylphenoxybenzenedisulfonate. The emulsifier was found to affect the relative molecular mass of polymethacrylamide, but it showed no effect on the polymerization rate. The transfer constant to the emulsifier determined amounts to 1,8 · 10^?2. The polymerization rate is proportional to the square root of the potassium peroxodisulfate concentration and to the first power of the methacrylamide concentration. During initiation by AIBN, the exponent of the concentration of AIBN in an equation expressing the dependence of the polymerization rate on AIBN concentration amounts to 0,82; the exponent of methacrylamide concentration is equal to 1. The activation energy for the polymerization initiated by K₂S₂O₈ is 67 kJ · mol^?1, whereas for the polymerization initiated by AIBN it is 44,0 kJ · mol^?1.     

Monomers for Adhesive Polymers, 7a

Homopolymerization and copolymerization of N‐(2‐hydroxyethylmethyl)acrylamide ( 1 ) with N,N′‐diethyl‐1,3‐bis(acrylamido)propane ( 2 ) have been studied in ethanol/water solvents or in bulk. The polymerization rate exponent depends on the polymerization temperature and increased from 0.99 at 50 °C to 1.21 at 75 °C. The initial polymerization rate dependence on temperature between 50 and 75 °C in Arrhenius coordinates was linear. However, the slope increased with an increase in monomer concentration. The overall activation energy E_a varied from 64 kJ · mol^?1 at 0.5 mol · L^?1 to 76 kJ · mol^?1 at 2.0 mol · L^?1 monomer concentration. In addition, the reaction order with respect to the initiator AIBN deviated from the standard free radical polymerization kinetics. The exponent 0.42 indicated a significant participation of primary radicals in termination reactions. The polymerization reaction order declined from ideality as well, and the E_a and polymerization enthalpy changed with the batch composition variation, which could be explained through monomer/monomer, monomer/solvent, or monomer/polymer complexation. The chain transfer to polymer was considered as an origin for the polymer network formation in monomer 1 homopolymerization if its concentration in the batch was 1 mol · L^?1 or higher. The more intensive polymerization acceleration with the monomer dilution and the greater heat released reduction with decrease in the monomer 1 to 2 ratios were evidenced in copolymerization. Nevertheless, the deviations from conventional reaction kinetics were not as pronounced as with acrylic or methacrylic acid polymerizations.

     

Study of the isothermal bulk polymerization of diallyl fumarate and related compounds by differential scanning calorimetry

Course and kinetics of the isothermal bulk polymerization of diallyl fumarate and the course of the polymerization of diallyl fumarate, diallyl maleate, and diallyl succinate by programmed heating were studied. 2,2′-Azoisobutyronitrile was used as initiator. The isothermal bulk polymerization was investigated at temperatures between 75 and 96°C and initiator concentrations ranging from 22,5 to 62,5 mmol/dm³ were applied. The bulk polymerization by programmed heating was investigated at temperatures between 40 and 190°C and at constant initiator concentration of 62,5 mmol/dm³. The negative value of the heat of isothermal bulk polymerization of diallyl fumarate at 75°C at the initiator concentration of 22,5 mmol/dm³ was found to be ?63,6 kJ/mol and to increase with increasing temperature to ?87,9 kJ/mol at 96°C. Also an increase was observed at higher initiator concentrations in the same temperature range. The initial rate constants for the isothermal bulk polymerization of diallyl fumarate were determined and from them the overall activation energy (100,4 kJ mol). It was found that the overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. The heats of the polymerization by programmed heating at constant initiator concentrations for diallyl fumarate, diallyl maleate, and diallyl succinate were found to be ?126,4, ?82,9, and ?90,8 kJ/mol, respectively. In all cases the DSC-curves display two peaks. On the basis of the results obtained, it was possible to interpret the differences in reactivity of individual functional groups in these compounds observed in programmed heating.     

Kinetics of the polymer-analogous reaction of poly[(methyl methacrylate)-co-(methacrylic acid)] with epichlorohydrin

Poly[(methyl methacrylate)-co-(glycidyl methacrylate)] (poly(MMA-co-GMA)) was obtained by polymer-analogous reaction of poly[(methyl methacrylate)-co-(methacrylic acid)] with an excess of epichlorohydrin (ECH) in the presence of a quaternary ammonium salt R₄NX as catalyst. The kinetics of the addition reaction and the consecutive transepoxidation reaction was studied at 50–90°C. The rate constant of the addition reaction is one order of magnitude higher with E₁ = 71 kJ · mol^?1 than that of the transepoxidation reaction with E₂ = 83 kJ · mol^?1. The rate constants rise linearly with increasing concentration of the catalyst R₄NX. The equilibrium constants K ≈ 2,3 of transepoxidation of glycidyl methacrylate (GMA) as well as of poly(MMA-co-GMA) both with 1,3-dichloropropane-2-ol were determined in butyl acetate and dimethylformamide as solvent at 80–100°C. During the reverse transepoxidation reaction of 3-chloro-2-hydroxypropyl methacrylate (CHPM) as well as of its MMA-copolymer with equimolar amounts of ECH, side products were formed from the beginning of the reaction and the equilibrium was not established. The addition of ECH to CHPM was observed as a side reaction.     

4-[Diphenyl(trimethylsilyl)methyl]benzophenone as initiator in the photopolymerization of methyl methacrylate and styrene

The polymerization of methyl methacrylate (MMA) and styrene (St) has been studied using 4-[diphenyl(trimethylsilyl)methyl]benzophenone 1 as photoinitiator. The polymerization follows a free radical mechanism; the polymerization rate increases linearly with the monomer concentration and was found to be proportional to the 0.33 and 1.40 power of the photoinitiator and the monomer (MMA) concentration, respectively. The overall activation energy in the case of MMA photopolymerization was calculated to be 25.0 kJ/mol. From ¹H NMR studies it is concluded that the obtained polymers contain two different trimethylsilyl moieties, one at the head and the other at the tail of the polymer chain, showing primary termination reactions even at low initiator concentrations. The p-benzoyltrityl radical 1^· is incorporated into the polymer chain to a very small extent, acting as a scavenger. This is also concluded by laser flash photolysis (LFP) and ESR spectroscopy measurements. A “living” character of the polymerization was observed only at very low initiator concentrations. The triplet state (³ 1 ^*) of the initiator was quenched by styrene, reducing its efficiency. The rate constant k_q of the quenching process of ³ 1 ^* was measured by LFP (k_q = 3.1 · 10⁹ M⁻¹ · S⁻¹). The triplet state and the photodissociation efficiency of the initiator is unaffected by MMA at various concentrations.     

Stabilizer‐Free Dispersion Copolymerization of Maleic Anhydride and Vinyl Acetate. II. Polymerization Features

Summary: The polymerization features of the novel stabilizer‐free dispersion copolymerization of MAn and VAc were studied. It was found that the dispersion copolymerization of MAn/VAc is a fairly rapid process, which starts from a slow solution polymerization (below 10% conversion, Stage I) and follows a drastic increase of polymerization rate (10–80% conversion, Stage II) due to the known gel effect. Such process was accompanied by the increase of molecular weight of the copolymer formed ( from 1.2 × 10⁴ to 3.8 × 10⁴ g · mol⁻¹) and the broadening of the molecular weight distribution ( from 2.4 to 8.0). E_a of Stage I was determined to be 76.7 kJ · mol⁻¹, while the value of Stage II was 64.7 kJ · mol⁻¹. The lower E_a in Stage II than that in Stage I suggests that there exists a shift of polymerization locus from the solution phase to the particle phase. Moreover, we found that the initial rate of polymerization increased with monomer concentration as well as initiator concentration, following the relationship (R_p)_i ∝ [MAn + VAc] · [BPO]. This further implies that the dispersion copolymerization mainly proceeds as a solution polymerization in the very early stage.

Evolutions of the stabilizer‐free dispersion copolymerization of MAn and VAc with butyl acetate as reaction medium and the solution copolymerization with methyl propyl ketone as solvent.     

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.     

Moisture-curable rubbers, 3. Moisture-cure of chlorosulfonated polyethylene

Chlorosulfonated polyethylene (CSM) was grafted with 3-aminopropyltriethoxysilane (APS) and the product was cured by exposing to moisture and by using dibutyltin dilaurate (DBTDL) as catalyst for condensation. The moisture-cured product showed a tensile strength of 7,8 MPa when the amount of APS added was 0,5 equivalent to the amount of chlorosulfonyl groups. The rate constant of the reaction of CSM with APS was found to be 8,5 · 10^?2 l · mol^?1 · s^?1 at 100°C in toluene, which is 850 times higher than that of the reaction of chlorinated butyl rubber with APS. The activation energy and the frequency factor of the reaction were 89 kJ · mol^?1 and 2,0 · 10¹¹ l · mol^?1 · s^?1, respectively. The activation energy of the moisture-cure of APS-grafted CSM was determined to be 44 kJ · mol^?1.     

Determination of absolute rate constants for radical polymerization and copolymerization of ethyl α-cyanoacrylate in the presence of effective inhibitors against anionic polymerization

The absolute rate constants of propagation k_p and of termination k_t of ethyl α-cyanoacrylate (ECNA) were determined in bulk at 30°C by means of the rotating sector method under conditions to suppress anionic polymerization; k_p = 1 622 1 · mol^?1 · s^?1 and k_t = 4,11 · 10⁸ 1 · mol^?1 · s^?1 for the polymerization in the presence of acetic acid, and k_p = 1610 1 · mol^?1 · s^?1 and k_t = 4,04 · 10⁸ l · mol^?1 · s^?1 for the polymerization in the presence of 1,3-propanesultone. The magnitude of k/k_t determined was 6,39 · 10^?3 l · mol^?1 · s^?1. The absolute rate constants for cross-propagation in ECNA copolymerizations were also evaluated. Quantitative comparison of the rate constants with those of common monomers and polymer radicals shows that the strong electron-withdrawing power of the ethoxycarbonyl and cyano groups enable the poly(ECNA) radical to add to monomers as fast as the other polymer radicals. The relatively high reactivity of ECNA, regardless of the type of attacking polymer radical, is interpreted by a transition state greatly stabilized by both the ethoxycarbonyl and the cyano groups.     

Homopolymerization of maleic anhydride

Pyridine and picoline initiated polymerizations of maleic anhydride were investigated in acetic anhydride. It was found that the electrical conductivity of the polymerizing mixture increases in the course of the reaction, and that the initial rate of polymerization increases with increasing monomer and pyridine concentrations, and its values, measured at different temperatures, show the apparent overall activation energy to be about 10 kcal/mol (41,87 kJ/mol). The rates of polymerization and the increase of specific conductivities of the reaction mixtures show the following order of initiator activity: γ-picoline > β-picoline > pyridine > α-picoline. Therefore, the results of the kinetic and conductivity measurements suggest that the polymerization rate depends on the basicity of the initiator.     

Polymerisation via macrozwitterions, 1. Ethyl and butyl cyanoacrylates polymerised by triethyl and triphenylphosphines

Anionic polymerisation of ethyl and butyl cyanoacrylates in THF initiated by triethyl and triphenylphosphines were followed by adiabatic calorimetry at temperatures between 20 and ?95°C. The polymers showed UV absorptions characteristic of phosphonium and cyanoacrylate carbanion end groups, indicating that the growing chains were macrozwitterions. Monomer conversion was quantitative and of 1st order in both monomer and initiator. Other criteria of ‘living’ polymerisation were satisfied, e.g. molecular weights corresponded to one chain per initiator molecule, and indicated that monomer added subsequently was incorporated on to previously formed chains. Assuming the overall rate to be that of propagation yielded values of k_p = 1 – 3 · 10⁵ dm³ · mol^?1 · s^?1 at ?78°C, with very low activation energies, i.e. 2,2 and 5,5 kJ · mol^?1 for ECA and BCA, respectively. Of a range of inert salts only LiBr significantly reduced the rate of polymerisation.