Kinetics of Radical Copolymerization. XII. Investigation of the Rate of Polymerization of the System Styrene-Butyl Acrylate-Benzene

The classical copolymerization rate equation does not describe the copolymerization rate in the styrene-butyl-acrylate-azoiso-butyronitrile-benzene-50°C system appropriately. The cross-termination coefficient (Π), calculated according to the classical rate equation, shows a strong monomer and solvent concentration dependence. The experimental results cannot be interpreted by the diffusion theory, penultimate effect, or the theory of charge transfer complexes. However, Π was found to be constant over the whole concentration range by the hot radical theory. Our kinetic data were consistently described by this theory, and its 13 parameters, characteristic of the copolymerization, were determined.     

Kinetics of Free Radical Copolymerization. VII. Kinetic Analysis of Ethyl Acrylate-Styrene Copolymerization in Inert Solvent

The copolymerization kinetics of the ethyl acrylate/styrene/azo-bis-isobutyronitrile/benzene/50°C system was found to deviate from the classical rate equation of copolymerization. The experimental results could not be interpreted by the diffusion theory, the penultimate effect, or the theory of electron donor-acceptor complexes. Our kinetic data were consistently described by the theory of hot radicals, and the 13 parameters characteristic for the copolymerization system were determined from an adequate number of data at different compositions by a nonlinear least-squares method.     

Copolymerization of N-vinylpyrrolidone with N,N-dimethyl-N,N-diallylammonium chloride

The possibility of synthesizing copolymers of N,N-dimethyl-N,N-diallylammonium chloride (DMDAAC) and N- vinylpyrrolidone (VP) was demonstrated and the features of radical copolymerization of these monomers in aqueous and alcohol media were investigated. The optimum conditions of conducting the reaction were determined and the kinetic features of the copolymerization reaction in the region of low degrees of conversion, for which the usual order mechanisms for radical polymerization are preserved, were investigated. The dependence of the initial rate of co polymerization on the composition of the starting mixture of comonomers is nonlinear, and the rate of copolymerization decreases significantly as the concentration of DMDAAC in the starting mixture increases. The composition of copolymers formed was studied and the copolymerization constants r₁ ^ef=r₂ ^ef=1 were calculated, i.e., the system is azeotropic, which is also detected for significant degrees of conversion.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1969–1973, September, 1990.     

Kinetics of Free Radical Copolymerization. IV. Rate of Initiation in the Copolymerization System Ethyl Acrylate-Styrene-Benzene

Dependence of the rate constant of initiation on the overall concentration and composition of monomer has been investigated in the free radical copolymerization of ethyl acrylate and styrene in bulk and in benzene solution at 50° C. The rate constant of initiation has been determined by the inhibition method using triphenyl-verdazil as the stable free-radical inhibitor. An equation has been derived to calculate the rate constant of initiation in a copolymerization system, where both monomers undergo a pseudounimolecular side reaction with the inhibitor. The rate constant of initiation in the copolymerization mixture is a linear composition of rate constants determined separately in the pure constituents of the system.     

Copolymerization Reactivities of α-Substituted Crotonyl Monomers

The radical copolymerizations of various α- substituted crotonyl monomers with styrene (St) and acrylonitrile (AN) were investigated, and the copolymerization parameters were determined by a least-squares procedure reported previously. The relative reactivities of the α-substituted crotonyl monomers toward polymer radicals of St and AN were found to correlate with the equation: log (relative reactivity of CH₃CH[dbnd]CXY) = ρ (σ + σ_Y) + A(Δlog Q_x + Δlog Q_Y), where Σ and Δlog Q are the polar Hammett and resonance substituent constants, respectively, and p and A are reaction constants. From the observed straight line relationships, the values of p and A were obtained to be as follows: ρ = 0.66, A = 0.75 for attack of poly-St radical, and ρ = -3.20, A = 1.3 for attack of poly-AN radical.     

Copolymerization of N-Vinylsuccinimide with Butyl Methacrylate in Pyridine

The kinetics of radical copolymerization of N-vinylsuccinimide with n-butyl methacrylate in pyridine was studied, and the previously unknown copolymerization constants of the monomers were determined. The calculations were performed using appropriate software and a new procedure for approximation of the experimental data, which allow determination of the kinetic parameters at high conversions with the minimum error. The copolymerization kinetics were compared for the reaction systems constituted by N-vinylsuccinimide and n-butyl methacrylate and by N-vinylsuccinimide and n-butyl acrylate.     

Radical Copolymerization of Acrylonitrile with Methyl Acrylate Complexed by Zinc Chloride

Abstract

The kinetics of the radical copolymerization of acrylonitrile with methyl acrylate complexed by zinc chloride (ZnCl₂) in dimethylformamide (DMF) was investigated at 60, 65, and 70°C. The kinetic data revealed that R_p was an inverse function of ZnCl₂ concentration and directly related to monomers concentration. The increase in the activation energy from 11.85 to 19.25 kJ·mol^?1 and the decrease in the value of the ratio of the propagation to termination rate constants (k_p ²/k_t ) from 0.08 to 0.06 L·mol^?1·s^?1 on the addition of ZnCl₂ indicated its retarding effect. The chain transfer constant of DMF for the system was 16.25 × 10^?4, accordingly the degree of polymerization decreased. The structure and composition of the copolymers determined by ¹H-NMR and elemental analysis was found to be alternating. The nonideal behavior of the glass transition temperatures determined by DSC also favors the alternation of monomer units in the copolymer. The reaction proceeds via a cross-propagation mechanism.     

Copolymerization and Copolymers of 2,4,5-Tribromostyrene with Methyl Acrylate and Methyl Methacrylate

Abstract

2,4,5-Tribromostyrene (TBSt) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in a toluene solution using 2,2′-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios were found to be for the system TBSt / MA r₁= 7.4 ± 1.2 (TBSt) and r₂= 0.1 ± 1.4 (MA) and for the system TBSt / MMA r₁ = 1.8 ± 0.2 (TBSt) and r₂ = 0.1 ± 0.2 (MMA). The e and Q values were also calculated. The initial rate of copolymerization, as well as molecular weight of the obtained copolymers for both system linearly increase as the content of TBSt in the monomer mixture increases. Similar behavior has also been established for the course of the copolymerization reactions to high conversions. The resulting copolymers rapidly decompose at temperatures 20–800°C above the decomposition of corresponding (metha)crylate hompolymers. However, the glass transition temperature increases markedly with increasing TBS content.     

Copolymers from Castor Oil Prepolymers (COP). 1. Copolymerization of Acrylonitrile with COP

The copolymerization of castor oil prepolymer (COP) was attempted with vinyl monomers in the presence of a free radical initiator at 75°C. It was found that acrylonitrile copolymerizes with COP in good yield, The copolymers were yellow brown in color and were soluble in hot dimethylformamide. The percentage composition of the copolymers was determined by the nitrogen of the copolymers. Their reactivity ratios were determined to be r₁ = 0.53, r₂ = 1.53.     

Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

Alternating Copolymerization of Styrene and N-(4-Bromophenyl)Maleimide

Abstract

Free radical copolymerization of styrene (St) and N(4-bro-mophenyl)maleimide (4BPMI) in dioxane solution gave an alternating copolymer in all proportions of feed comonomer compositions. The monomer reactivity ratios were found to be r ₁, = 0.0218 ± 0.0064 (St) and r ₂, = 0.0232 ± 0.0112 (4BPMI), and the activation energy of the copolymerization reaction for the equimolar ratios of comonomer was E _a, = 51.1 kJ/mol. The molecular weights of the copolymers obtained are relatively high, the T _g's showed similar values (490 K), and the thermal stability is higher than that of polystyrene. The initial rate of copolymerization depends on the total concentration of the comonomers and the maximum occurred at higher 4BPMI mol fractions; however, the overall conversion is highest at equimolar comonomer composition. It has been shown that a charge-transfer complex participates in the process of copolymerization. The initial reaction rate was measured as a function of the monomer molar ratios, and the participation of the charge-transfer complex monomer and the free monomers was quantitatively estimated.     

Copolymerization and Copolymers of 2,4,5-Tribromostyrene with Styrene and Acrylonitrile

Abstract

2,4,5-Tribromostyrene (TBSt) was copolymerized with styrene (St) or acrylonitrile (AN) in toluene solution using 2,2′-azobisisobutyronitrile as free radical initiator. The copolymerization reactivity ratios were found to be for the system TBSt/St r ₁ = 1.035 ± 0.164 (TBSt) and r ₂ = 0.150 ± 0.057 (St), and for the system TBSt/AN r ₁ = 2.445 ± 0.270 (TBSt) and r ₂ = 0.133 ± 0.054 (AN). The e and Q values were also calculated. The initial copolymerization rate, R _p, for both systems linearly increases as the content of TBSt in the monomer mixture increases. However, these values are somewhat higher when AN was used as a comonomer. A similar behavior has also been established for the course of the copolymerization reactions to high conversion. The resulting copolymers and TBSt-homopolymer show similar thermal stabilities of polystyrene. However, the glass transition temperature increases markedly with increasing TBSt content.     

Radiation-Induced Copolymerization of Thiophene with Maleic Anhydride

Radiation-induced copolymerization of thiophene with maleic anhydride has been studied. On the copolymerization in chloroform solution, the effects of dose rate, polymerization temperature, and, monomer composition and concentration on the yield and molecular weight of the copolymer were determined. The copolymerization proceeds via a radical mechanism with bimolecular termination of propagating polymer radicals, and the apparent activation energy is 5.3 kcal/mole. By NMR spectroscopy of copolymer, it was also found that these monomers copolymerize alternately to give a copolymer having structure I. In this copolymerization, the higher initial rates were obtained at an equimolar composition of monomers and by using solvents containing chlorine, such as CC1₄, CHC1₃, and C₆H₅C1.     

Tandem Isomerization and Cationic Copolymerization of Allyl Ethers

Abstract

A new catalyst system comprising a combination of dicobalt octacarbonyl and a hydridosilane has been successfully employed for the tandem isomerization and cationic copolymerization of 1-allyloxy-2-phenoxyethane (M₁) and l-allyloxyoctane (M₂). Reactivity ratios of r₁ = r₂ = 0.58 ± 0.01 were calculated for these monomers by both the Mayo-Lewis and the Fineman-Ross methods which are indicative of a statistical copolymerization. A GPC study of the copolymerization showed that only copolymers were obtained. This data further indicates that the isomerization of the individual monomers and their subsequent copolymerization proceed at very nearly identical rates. The copolymerization of allyl ether monomers presents an opportunity for designing novel polymers with tailored properties.     

Copolymerization of vinyl cyclohexane and α-methyl vinyl cyclohexane with acrylonitrile

Copolymerization of vinyl cyclohexane and α-methyl vinyl cyclohexane with acrylonitrile in the presence of a complexing agent AlEtCl₂ results in the formation of alternate copolymers. In the copolymerization of vinyl cyclohexane with acrylonitrile the copolymer composition depends on the ratio of acrylonitrile to AlEtCl₂. If this ratio is unity, alternating copolymers of the composition 1:1 are formed; with a ratio greater than unity statistical copolymers that contain more than 50% acrylonitrile units are produced. The ¹H-NMR spectroscopy measurements indicate that the interaction between the comonomers and the complexing agent leads to the formation of ternary donor–acceptor complexes of equimolar composition. The equilibrium constants of these complexes at ?60°C have been determined. The effects of temperature, nature of solvent and dilution on the yield, and composition of the copolymers of vinyl cyclohexane with acrylonitrile formed have been studied. By lowering the temperature the yield of copolymers increases but their composition remains equimolar. An increase in the polarity of the medium results in an increase in copolymer yield, whereas the yield decreases if the reaction is conducted in a donor-solvent medium. Dilution of the reaction mixture disrupts the alternation of units in the macrochain of copolymers. The kinetic pecularities of copolymerization have been investigated. The linear dependence of the copolymerization rate on the product of comonomer concentration is observed. The rate of copolymerization is proportional to the square root of the incident light intensity. Various additions of radical type and irradiation accelerate the process of copolymerization. The mechanism of alternating copolymerization of vinyl cyclohexane monomers with acrylonitrile in the presence of AlEtCl₂ is discussed in terms of homopolymerization of the comonomer complex.     

Chain-Length Distributions in Living Copolymerization Systems

ABSTRACT

An asymptotic theory for living copolymerization is illustrated by comparison with numerical calculations of the chain-length distribution (CLD). A new representation of the CLD in reduced coordinates using stretching parameters from the asymptotic theory is seen to give much clearer insight into the system behavior with time. Use of the asymptotic theory for the prediction of the CLD properties when there are large variations in monomer composition is discussed.     

Studies of the polymerization of diallyl compounds. XXVII. Copolymerization of diallyl tartrate with several vinyl monomers

The radical copolymerization of diallyl tartrate (DATa) (M₁) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r₁r₂, were obtained. In the copolymerization with ABz or VAc (M₂), the r₁ and r₂ values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r₁r₂ for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen-bonding ability of DATa.     

Copolymerization of <Emphasis Type="Italic">p</Emphasis>-(2,2-dichlorocyclopropyl)styrene with Methyl methacrylate and properties of the resulting copolymers

A copolymer based on p-(2,2-dichlorocyclopropyl)styrene and methyl methacrylate was prepared by radical copolymerization. The copolymerization constants were determined, and the parameters of the Q-e scheme were calculated.     

Cationic Copolymerization of Propylene Oxide with Tetrahydrofuran. XI. Calculation of Individual Rate Constants

Rate constants (k₁ k₁₁, k₁₂, k₂₂, k₂₁ and k_t) for various steps involved in the copolymerization of propylene oxide (PO) with tetrahydrofuran (THF) have been calculated from reaction rate data obtained with the following catalyst system: (a) triphenyl-methyl cations ((C₆H₅)₃C⁺) associated with hexafluorophosphate (PF₆ ^?), hexafluoroarsenate (AsF₆ ^?) and hexafluoroantimonate (SbF₆ ^?) gegenions; (b) antimony pentachloride (SbCl₅); and, (c) boron trifluoride etherate, BF₃:(C₂H₅)₂O. The latter two systems were studied in the presence of cocatalysts. The effects of several parameters (the cocatalyst concentration and bulk size, the nature of the solvent, and the reaction temperature) on the rate constants are highlighted. The role of entropy in the initiation, propagation and termination steps is discussed in terms of solvation and desolvation processes. Based on termination activation energy considerations, the order of stability for the gegenions used in the copolymerization of PO with THF was found to be: AsF₆ ^? > SbF₆ ^? > HOBF₃ ^?PF₆ ^? > SbCl₆ ^?     

A Kinetic Study of Free-Radical Styrene-Acrylonitrile Copolymerization by Differential Scanning Calorimeter

Abstract

The isothermal free-radical copolymerization of styrene and acrylonitrile was examined in the temperature range of 333-373 °K. Initial rate studies of styrene homopolymerization were conducted and agreed favorably with values in the literature. Initial rate studies for acrylonitrile solution polymerization in DMF were also performed. Initiator decomposition rate constants measured in the presence of AN and styrene monomer are reported for AIBN, BP, and DTBP. Rate functions for the full spectrum of comonomer compositions initiated by AIBN and benzoyl peroxide are reported. Several copolymerization kinetic models were tested and found to be inadequate. Conversion histories were found to be consistent with observed initial rates and follow a simple pseudohomopolymerization kinetic model. Autoacceleration was observed and found to increase in severity with increased AN feed compositions and decreased reaction temperatures.