Effect of Substituents on the Copolymerization Parameters of Some Phenolic Monomers

Copolymerization parameters of some halogen substituted phenolic monomers have been determined by the linear graphical method of Kelen and Tüdös. The order of reactivity of p-chlorophenol, p-bromophenol and p-iodophenol is found to be the reverse of the order of electronegativity of their halogen substituents when they are copolymerized with p-hydroxy-benzoic acid. On copolymerization with p-cresol, these halogen substituted phenols have reactivity in the same order as the electronegativity of their substituents. This reversal of reactivity of phenolic monomers has been interpreted in terms of (1) opposite polarization caused by electrophilic or nucleophilic substituents present in the common monomers, and (2) the magnitude of their resonance stabilization.

The copolymerization parameters r₁ and r₂ are universally used for the characterization of monomer pairs with regard to their behavior in copolymerization. The classic copolymer equation describes the composition of the copolymer as a function of the reactivity ratios and the composition of the monomer feed. Several authors have used linear [1], nonlinear [2–6], specific coper composition equations [7], and computer programming routines [8] for calculating copolymerization parameters r_l and r₂. Kelen and Tödös [9] have recently.     

p-ACETYLBENZYLIDENE TRIPHENYLARSONIUM YLIDE (p-ABTAY) INITIATED RADICAL COPOLYMERIZATION OF METHYLMETHACRYLATE WITH STYRENE

p-Acetylbenzylidene triphenylarsonium ylide (p-ABTAY) initiated radical copolymerization of methylmethacrylate (MMA) with styrene in dioxane, at 60 ± 0.1°C, under the inert atmosphere of nitrogen yields alternating copolymer, as evidenced by ¹H NMR spectroscopy. The kinetic equation for the present system is Rp μ[p-ABTAY]^0.46 [MMA] [Sty]. The rate of copolymerization (Rp) is proportional to the square root of [p-ABTAY] indicating bimolecular termination. The values of kp²/kt and energy of activation have been computed as 6.3 × 10^?3 l mol^?1s^?1 and 63 KJ mol l^?1, respectively. The reactivity ratios have been calculated as r₁ (MMA) = .60, r₂ (Sty) = .35, by using the Kelen-Tudös method. The copolymerization reaction is initiated by the phenyl free radical. The formation of phenyl radicals may be attributed to the pp-dp overlap between the hybridized sp² orbital and the larger and more diffuse 4d orbital of arsenic.     

Rates of copolymerization of acrylonitrile and ethylenesulfonic acid

Use was made of differential absorption in the near-infrared region to follow the rates of copolymerization of acrylonitrile (AN, M₁) with ethylenesulfonic acid (ESA, M₂) in aqueous zinc chloride solution. The concentrations of the monomers were followed separately and simultaneously. It was found experimentally that the ratios d log [M₁]/dt and d log [M₂]/dt were each constant. This was interpreted to mean that the product of the reactivity ratios of the two monomers (r₁,r₂) is unity and that the ratio of termination rate constants is equal to the propagation reactivity ratio. It was found that d log [M₁]/d log [M₂] = r₁ = 4.5₂. This value is in fair agreement with polymer composition data obtained independently. In the Q—e system the equality r₁r₂ = 1 is equivalent to the monomers having equal e values. Thus, in the AN—ESA system, P₁/P₂ = k₁₁/k₂₁ = k₁₂/k₂₂ = k_1T/k_2T, where P₁ is the resonance constant of polymer radicals ending in units of M₁; and k₁₁, k₁₂, and k_1T are the rate constants involving the reaction of this radical with M₁, M₂, and T (terminating agent), respectively. A gel effect was not observed even at M₁ conversions as high as 88%.     

Copolymerization of Allilidene Diacetate with Vinyl Acetate

Abstract

The monomer reactivity ratios for vinyl acetate (VAc)-allilidene diacetate (ADA) copolymerization have never been obtained. The composition of VAc-ADA copolymers was determined by NMR spectroscopy, measuring CH protons corresponding to ADA at 3.1τ and VAc at 5.1τ. The monomer reactivity ratios were evaluated; r₁ = 1.34 ± 0.05 and r₂ = 0.48 ± 0.03, where M₁ = ADA and M₂ = VAc. From these values the Q and e values for ADA were calculated: Q = 0.047 and e = 0.44 by taking Q = 0.026 and e = ?0.22 for VAc. The H value [1] for copolymerization of ADA, VAc, and vinyl chloride (VC) is 0.87.     

Phenolic resins for solid-phase peptide synthesis: Copolymerization of styrene and p-acetoxystyrene

Details are given of the synthesis and purification of p-acetoxystyrene and its solution and suspension copolymerization with styrene. Reactivity ratios, evaluated by the Tidwell-Mortimer method, were r₁ (p-acetoxystyrene) = 1.18, and r₂ (styrene) = 0.88 for (bulk) solution copolymerization. Corresponding values of the reactivity ratios for suspension copolymerization were, within experimental error, indistinguishable from unity. Thus the copolymer composition is governed simply by the monomer feed composition. Use of a specially designed reactor vessel permits convenient suspension copolymerization of styrene, p-acetoxystyrene, and divinylbenzene to give crosslinked resins having comparatively narrow particle size distributions. Acetoxy groups in the crosslinked resin are cleaved by hydrazine hydrate under very mild conditions to give crosslinked polystyrenes having phenolic groups which, in turn, provide a useful alternative to the more usual chloromethylated polystyrene resins for solid-phase peptide synthesis.     

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.     

Kinetics of radical copolymerization of [1‐(fluoromethyl)vinyl]benzene with chlorotrifluoroethylene

The synthesis of [1‐(fluoromethyl)vinyl]benzene (or α‐(fluoromethyl)styrene, FMB) and its radical copolymerization with chlorotrifluorethylene (CTFE), initiated by tert‐butyl peroxypivalate (TBPPi) are presented. The allyl monomer [H₂C = C(CH₂F)C₆H₅] was obtained by electrophilic fluorodesilylation of trimethyl(2‐phenylprop‐2‐en‐1‐yl)silane in 93% yield. A series of seven copolymerization reactions were carried out starting from initial [CTFE]₀/([FMB]₀ + [CTFE]₀) molar ratios ranging from 19.6 to 90.0 mol %. The molar compositions of the obtained poly(CTFE‐co‐FMB) copolymers were assessed by means of ¹⁹F nuclear magnetic resonance spectroscopy. Statistic copolymers were produced with molar masses ranging between 13,800 and 25,600 g/mol. From the Kelen and Tudos method, the kinetics of the copolymerization led to the determination of the reactivity ratios, r_i, of both comonomers (r_CTFE = 0.4 ± 0.2 and r_FMB = 3.7 ± 1.8 at 74 °C) showing that FMB is more reactive than CTFE as well as other halogenated or nonhalogenated monomers involved in the radical copolymerization with CTFE. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3843–3850, 2007     

Kinetic Studies on the Copolymerization of Acrylonitrile and Itaconic Acid in Dimethylsulfoxide

The free radical copolymerization of acrylonitrile (AN) with itaconic acid (IA) in dimethylsulfoxide (DMSO) initiated by azobisisobutyronitrile (AIBN) has been found to be chemically controlled even at high conversion. In order to explain this specific finding by Walling's kinetic model, a detailed study on the monomer reactivity ratios (MMRs), decomposition kinetics of AIBN and homopolymerization kinetics of AN was carried out in DMSO from 50 to 80°C. The results suggest that the reactivity ratio of IA is less than unity and always larger than that of AN. Thus, the reaction has an ideal copolymerization behavior when the temperature is increased. It is also found that decomposition of AIBN in DMSO is strictly first order and the decomposition rate constants (k _d) determined by nitrogen evolution technique are acceptable. k_p /k ^0.5 _t ratios of AN were estimated from the off-line conversion data under various monomer and initiator concentration. Additionally, the temperature dependences on MRRs, k _d and k_p /k ^0.5 _t were believed to follow the Arrhenius's law very well.     

Radical Copolymerization of Vinylidene Chloride with 3(2-Methyl)-6-methylpyridazinone in Several Solvents

The radical copolymerization of vinylidene chloride (Vc, M₁) with 3(2-methyl)-6-methylpyridazinone (I, M₂) was carried out in benzene, ethanol, phenol, and acetic acid at 60 and 80°C. The monomer reactivity ratios were found to vary with the reaction conditions. The linear correlationships were obtained by plotting the values of log r₁ against those of ^V C[dbnd]O and ^V C[dbnd]C of monomers determined in the solvents.     

Kinetic and ESR studies on radical copolymerization of p-tert-butoxystyrene and di-n-butyl maleate in benzene

The copolymerization of p-tert-butoxystyrene (TBOSt) (M₁) and di-n-butyl maleate (DBM) (M₂) with dimethyl 2,2′-azobisisobutyrate (MAIB) in benzene at 60°C was studied kinetically and by means of ESR spectroscopy. The monomer reactivity ratios were determined to be r₁ = 2.3 and r₂ = 0 by a curve-fitting method. The copolymerization system was found to involve ESR-observable propagating polymer radicals under practical copolymerization conditions. The apparent rate constants of propagation (k_p) and termination (k_t) at different feed compositions were determined by ESR. From the relationship of k_p and f₁ (f₁ = [M₁]/([M₁] + [M₂])) based on a penultimate model, the rate constants of five propagations of copolymerization were evaluated as follows; k₁₁₁ = 140 L/mol s, k₂₁₁ = 3.5 L/mol s, k₁₁₂ = 61 L/mol s, k₂₁₂ = 1.5 L/mol s, and k₁₂₁ = 69 L/mol s. Thus, a pronounced penultimate effect was predicted in the copolymerization. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1449–1455, 1998     

Effects of temperature on styrene–methacrylonitrile copolymerization

The free-radical copolymerization of styrene and methacrylonitrile was studied in toluene solution at 60, 90, and 120°C. Copolymer composition was estimated from gas-chromatographic measurement of unreacted monomer concentrations. Reactions were carried to about 20% conversion to minimize analytical errors. Reactivity ratios were calculated by using an integrated form of the Mayo-Lewis simple copolymerization equation. Reactivity ratios were not sensitive to reaction temperature. The values at 90°C are r₁ = 0.41 (methacrylonitrile) and r₂ = 0.37 (styrene). The r₁ values are higher than those reported by other workers, presumably because of advantages in the present analytical technique and calculation method. The negligible temperature dependence of reactivity ratios is in accord with theory. If monomer pairs exhibit pronounced dependence of reactivity ratios on polymerization temperature, this may indicate a change in mode of placement of units in the polymer chain.     

Anionic copolymerization of optically active α-methylbenzyl methacrylate and trityl methacrylate. I. Reactivity of monomers

The monomer reactivity ratios were determined in the anionic copolymerization of (S)- or (RS)-α-methylbenzyl methacrylate (MBMA) and trityl methacrylate (TrMA) with butyllithium at ?78°C, and the stereoregularity of the yielded copolymer was investigated. In the copolymerization of (S)-MBMA (M₁) and TrMA (M₂) in toluene the monomer reactivity ratios were r₁ = 8.55 and r₂ = 0.005. On the other hand, those in the copolymerization of (RS)-MBMA with TrMA were r₁ = 4.30 and r₂ = 0.03. The copolymer of (S)-MBMA and TrMA prepared in toluene was a mixture of two types of copolymer: one consisted mainly of the (S)-MBMA unit and was highly isotactic and the other contained both monomers copiously. The same monomer reactivity ratios, r₁ = 0.39 and r₂ = 0.33, were obtained in the copolymerizations of the (S)-MBMA–TrMA and (RS)-MBMA–TrMA systems in tetrahydrofuran (THF). The microstructures of poly[(S)-MBMA-co-TrMA] and poly-[(RS)-MBMA-co-TrMA] produced in THF were similar where the isotacticity increased with an increase in the content of the TrMA unit.     

Synthesis of Graft Polymers by Copolymerization of Macromonomers. II. Copolymerization Kinetics of Styrene-and Methacrylate-Terminatedpoly(2-Acetoxyethyl Methacrylate) Macromonomers

Styrene-terminated poly(2-acetoxyethyl methacrylate) macromonomer (EBA), methacrylate-terminated poly(2-acetoxyethyl methacrylate) macromonomer (MPA), and methacrylate-terminated poly(methyl methacrylate) macromonomer (MPM) were synthesized and subjected to polymerization and copolymerization by a free-radical polymerization initiator (AIBN). EBA and MPA were homopolymerized at various concentrations. EBA exhibited higher reactivity than styrene. The reactivity of MPA, however, was almost equal to that of glycidyl methacrylate. Cumulative copolymer compositions were determined by GPC analysis of copolymerization products. The reactivity ratios estimated were r_a = 0.95 and r_b , = 0.90 for EBA macromonomer (a)-methyl methacrylate (b) copolymerization. These values were not consistent with literature values for the styrene-methyl methacrylate and p-methoxy-styrene-methyl methacrylate systems. The reactivity ratios estimated for MPA and 2-bromoethyl methacrylate were r_a - 0.95 and r_b , = 0.98; equal to the glycidyl methacrylate-2-bromoethyl methacrylate system. MPA or MPM was also copolymerized with styrene, and the reactivity ratios were r_a = 0.40, r_a = 0.60 and r_a = 0.39, r_a = 0.58, respectively. These estimates were in good agreement with the reactivity ratios for glycidyl methacrylate and styrene. Thus, no effect of molecular weight was observed for both copolymerization systems.     

Free Radical Copolymerization of N‐Cyclohexylmaleimide with Cyclohexene

The radical copolymerization of cyclohexene (M₁) and N‐cyclohexylmaleimide (M₂) was carried out with 2,2′‐azobis(isobutyronitrile) as an initiator in various solvents at 55°C. The copolymerization of cyclohexene with N‐cyclohexylmaleimide in chloroform, dioxane and benzene proceeded in a homogeneous system to give an alternating copolymer when the monomer of cyclohexene was over 40 mol% in the feed. It was found that the initial rate of the copolymerization (R_p), as well as the number‐average molecular weight of copolymers, were dependent on the monomer composition and was at maximum at about 30 mol% of cyclohexene in the feed. The effects of solvents on the R_p and reactivity ratios were also investigated in this copolymerization system. The copolymerization in dioxane produced a higher R_p than that in chloroform and benzene, and the monomer reactivity ratios were found to be r₁=0, r₂=0.032 in chloroform; r₁=0, r₂=0.065 in benzene and r₁=0, r₂=0.14 in dioxane, respectively.     

Ethylene/hexene copolymerization with the heterogeneous catalyst system SiO2/MAO/rac‐Me2Si[2‐Me‐4‐Ph‐Ind]2ZrCl2: The filter effect

The main focus of this study is the ethylene/hexene copolymerization with the silica supported metallocene SiO₂/MAO/rac‐Me₂Si[2‐Me‐4‐Ph‐Ind]₂ZrCl₂. Polymerizations were carried out in toluene at a reaction temperature of 40°C–60°C and the cocatalyst used was triisobutylaluminium (TIBA). The kinetics of the copolymerization reactions (reactivity ratios r_E/H, monomer consumption during reaction) were investigated and molecular weights M_w, molecular weight distributions MWD and melting points T_m were determined. A schematic model for the blend formation observed was developed that based on a filtration effect of monomers by the copolymer shell around the catalyst pellet.     

Effects of complexing agents in radical copolymerization

Radical copolymerization of methyl methacrylate (MMA, M₁) with various monomers has been studied in presence of modifiers, i.e., complexing agents (CA): ZnCl₂, AlCl₃, AlBr₃, Al(C₂H₅)₂Cl, forming coordinate complexes with ester group of the monomer and of the propagating radical. The comonomers of the first group form complexes of similar structure and stability as MMA, methyl acrylate, or butyl acrylate. The comonomers of the second group do not form complexes with the modifiers (vinylidene chloride, 2,6-dichlorostyrene, p-chlorostyrene, styrene). For all systems studied the copolymer composition follows the Mayo-Lewis equation. In the first group of the systems the effective reactivity ratios (r₁, r₂) approach unity with increase of the CA molar content (r₁ = r₂ ? 1 at [(CA)/MMA] + [MA] ≥ 0,3) In the second group of the systems the values of r₁ either increase to a limit value (at [CA]/[MMA] ≥ 0.3), pass through maximum, or decrease to a limiting value with the CA molar content. The values of r₂ decrease in all systems. The character of variation of r₁ and r₂ has been explained in terms of effects of the CA's on reactivity of MMA and PMMA radical. The equations for the copolymer compositions in these systems have been derived.     

Radical-initiated homo- and copolymerizations of methacryloyl fluoride

The kinetics of methacryloyl fluoride (MAF) homopolymerization was investigated in methyl ethyl ketone (MEK) with azobis(isobutyronitrile) as initiator. The rate of polymerization (R_p) followed the expression R_p = k[AIBN]^0.55[MAF]^1.18. The overall activation energy was calculated as 74.4 kJ/mol. The relative reactivity ratios of MAF(M₂) copolymerization with styrene (r₁ = 0.083, r₂ = 0.14), and methyl methacrylate (r₁ = 0.48, r₂ = 0.81) in methyl ethyl ketone were obtained. Application of the Q–e scheme (in styrene copolymerization) led to Q = 2.22 and e = 1.31. The glass transition temperature (T_g) of poly(MAF) was 90°C by thermomechanical analysis. Thermogravimetry of poly(MAF) showed a 10% weight loss of 228°C in air.     

Effect of Solvent on the Radical Copolymerizability of Styrene with 3(2-Methyl)-6-methylpyridazinone

Abstract

The radical copolymerization of styrene (St, M₁) with 3(2-methyl)-6-methylpyridazinone (I, M₂) has been carried out in several p-substltuted phenols at 60 and 70°C. Monomer reactivity ratios (r₁) and activation parameters of copolymerization were found to be affected by phenols. The values of the activation energy (δδE?) and entropy (δδS?) increased with the increase of the interaction of I with the solvents. Linear relationships were observed between the [sgrave]-values of p-substituents of phenols and the values of log 1/r₁ and also of δδE? and δδS?. The radical copolymerization of St (M₁) with 6-substituted 3(2-methyl)-pyridazinone was also carried out.     

Alternating copolymerization of ethylene with maleic anhydride

The copolymerization of ethylene with maleic anhydride was carried out with γ-radiation and a radical initiator, i.e., 2,2′-azobisisobutyronitrile and diisopropyl peroxydicarbonate under pressure at various reaction conditions. The homopolymerization of neither monomer was observed in this system. In the γ-ray-initiated copolymerization the G value (polymerized monomer molecules per 100 e.v.) was shown to be between 10³ and 10⁴. It was found that the dose rate exponent of the rate is approximately unity, and the rate is proportional to the amount of ethylene monomer. Apparent activation energies of 1.8 and 27.5 kcal./mole were obtained for γ-ray-initiated and AIBN-initiated copolymerization, respectively. Since the composition of copolymer is independent of monomer molar ratio and the molar ratio of ethylene to maleic anhydride in the polymer is approximately unity, the monomer reactivity ratios were obtained as r_E ? 0 and r_M ? 0 for γ-ray-initiated polymerization at 40°C. Alternating copolymerization was, therefore, concluded to occur. Infrared analysis of the copolymer is almost consistent with this. The copolymer in the solid state is amorphous. It is soluble in water, cyclohexane, and dimethylformamide and insoluble in lower alcohols, ether, and aromatic hydrocarbons. The aqueous solution of polymer gave a strong acid.