Quinone copolymerization. I. Reactions of p-chloranil,p-benzoquinone,and 2,5-dimethyl-p-benzoquinone with vinyl monomers under free-radical initiation

The free-radical copolymerization reactions of p-chloranil, p-benzoquinone, and 2,5-di-methyl-p-benzoquinone with vinyl monomers were studied. Reactions of p-chloranil with styrene yielded copolymers of approximately 1:1 composition under a variety of reaction conditions. A copolymer containing a block of 1:1 of styrene:p-chloranil and a block of polystyrene was prepared. Several styrene-like monomers copolymerized with p-chloranil to yield copolymrs possessing considerable amounts of incorporated quinone. p-Benzoquinone copolymerized with 1,3-butadiene and 2-vinyl-pyridine to yield copolymers of significant molecular weights. Reactions of 2,5-dimethyl-p-benzoquinone with vinyl monomers did not yield any isolable polymeric products.     

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.     

Kinetics of the copolymerization of styrene with small quantities of divinylbenzenes

The study of copolymerization of styrene with small amounts (≤0.04 wt %) of divinylbenzenes (DVB) offers advantages over similar studies made at high DVB concentrations. A simple set of equations can be used to describe the kinetics of copolymerization at low DVB concentrations. Experimental data show that the copolymerization constants (r₂) for the copolymerization of the first double bonds of m- and p-DVB (monomer 1) with styrene (monomer 2) are 0.85 and 0.43, respectively. In contrast to findings at higher DVB concentrations these constants do not change during the first half of the polymerization. After 50% conversion an autoacceleration effect reduces the selectivity of the growing polystyrene radical. The copolymerization constants for the second double bonds of m- and p-DVB during the first half of the polymerization are estimated as 1.     

ON THE KINETICS AND MECHANISM OF THE COPOLYMERIZATION OF ACRYLONITRILE WITH STYRENE IN THE PRESENCE OF COPPER CHLORIDE

The copolymerization of styrene (St) and acrylonitrile (AN) complexed with CuCl_2 monomer by a free radicalmechanism was performed using benzoyl peroxide as an initiator at 65℃ under N_2 atmosphere for 150 min. The rate ofpolymerization (R_p) was found to increase linearly with the concentration (in mol/L) of CuCl_2, AN and St through scalingrelations. The activation energy of the copolymerization process in the presence and absence of CuCl_2 was found to be46.5 kJ/mol and 102 kJ/mol, respectively. The viscosity average molecular weigh of the copolymer and the k_p~2/k_t ratio weredctermired to further assess the accelerating effect of CuCl_2 on the copolymerization process. The copolymerization processin the presence of CuCl_2 has a radical complex mechanism.     

Effect of reaction medium on the ionizing radiation-initiated cationic copolymerization of styrene derivatives

The influence of reaction medium polarity on the ionizing radiation-initiated copolymer-ization of styrene derivatives involving unpaired carbocations is examined. In the copo-lymerization of nonpolar monomers such as p-CH3styrene/styrene, a small effect consistent with that predicted by Laidler-Eyring theory is found. In the copolymerization of nonpolar/polar monomer pairs such as p-CH3styrene/p-Clstyrene and styrene/p-Clstyrene, any such effect is masked by specific solvation phenomena. A competition between such phenomena appears to exist, in which the different cations are dominated by different interactions. The p-Clstyryl cation appears to undergo strong intramolecular complexation with the penultimate aromatic ring in nonpolar conditions; thus, this cation displays increased se-lectivity toward monomers best able to disrupt the complex. The p-CH₃styryl and styryl cations do not appear to be subject to such strong complexation; thus, in nonpolar solvent, their selectivity tends towards monomers with the highest cation-solvating ability. The differing copolymerization behavior of the p-Clstyryl cation is consistent with the findings of previous investigations of the effect of reaction medium on chain transfer with these monomers. © 1995 John Wiley & Sons, Inc.     

Mechanism of emulsion polymerization of styrene using a reactive surfactant

The emulsion polymerization of styrene using the reactive surfactant sodium dodecyl allyl sulfosuccinate (TREM LF‐40) was studied. The polymerization kinetics were found to be unusual in that R_p was not directly proportional to N_p (R_p ∝ N_p^0.67). Several reasons are stated to explain the unusual kinetics, including chain transfer to TREM LF‐40, copolymerization of styrene with TREM LF‐40, and the influence of the homopolymer of TREM LF‐40 [poly(TREM)] and/or the copolymer [poly(TREM‐co‐styrene)] on the entry and exit rates of free radicals. The possibility of both chain transfer and copolymerization exists primarily at the oil/water interface, whereas both can also occur in the aqueous and monomer phases. Bulk polymerizations of styrene in the presence of TREM LF‐40 and poly(TREM) were conducted, and the results show that the reaction rate decreased for the styrene/TREM LF‐40 system. Latex characterization by serum replacement and titration measurements provided evidence for the chemical bonding of TREM LF‐40 to the polymer particles. The fraction of chemically bound reactive surfactant decreased with increasing surfactant concentration and increased with increasing initiator concentration. Relatively high contact angles of water on films cast from the latexes showed that TREM LF‐40 did not migrate significantly to the surface of the film, which was consistent with the latex‐surface characterization results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3093–3105, 2001     

Kinetics of free-radical copolymerization of α-methylstyrene and styrene

The free-radical copolymerization of α-methylstyrene and styrene has been studied in toluene and dimethyl phthalate solutions at 60°C. Gas chromatography was used to monitor the rate of consumption of monomers. For styrene alone, the measured rate of polymerization R_p and M?_n of the polymer coincided with values expected from previous studies by other workers. Solution viscosity η affected R_p and M?_n of styrene homopolymers and copolymers as expected on the basis of an inverse proportionality between η^1/2 and termination rate. The rate of initiation by azobisisobutyronitrile appears to be independent of monomer feed composition in this system. Molecular weights of copolymers can be accounted for by considering combinative termination only. The effects of radical chain transfer are not significant. A theory is proposed in which the rate of termination of copolymer radicals is derived statistically from an ideal free-radical polymerization model. This simple theory accounts quantitatively for R_p and M?_n data reported here and for the results of other workers who have favored more complicated reaction models because of the apparent failure of simple copolymer reactivity ratios to predict polymer composition. This deficiency results from systematic losses of low molecular weight copolymer species in some analyses. Copolymer reactivity ratios derived with the assumption of a simple copolymer model and based on rates of monomer loss can be used to predict R_p values measured in other laboratories without necessity for consideration of depropagation or penultimate unit effects. The 60°C rate constants for propagation and termination in styrene homopolymerization were taken to be 176 and 2.7 × 10⁷ mole/l.-sec, respectively. The corresponding figures for α-methylstyrene are 26 and 8.1 × 10⁸ mole/l.-sec. These constants account for the sluggish copolymerization behavior of the latter monomer and the low molecular weights of its copolymers. The simple reaction scheme proposed here suggests that high molecular weight styrene–α-methylstyrene copolymers can be produced at reasonable rates at 60°C by emulsion polymerization. This is shown to be the case.     

Synthesis of networked polystyrene endowed with nucleophilic reaction sites by the living anionic polymerization technique

The living anionic copolymerization of styrene with 1,2‐bis(4′‐ethenylphenyl)ethane (1) or p‐divinylbenzene (PDVB) with sec‐butyllithium in benzene was carried out. The copolymerizations of styrene with more than 20 mol % of 1 gave insoluble polymers in quantitative yields, whereas the yield showed the maximum (97%) for PDVB at 15 mol %. The content of unreacted double bonds of the network polymer formed by the copolymerization with PDVB was four times as large as that formed with 1. Gas chromatographic analyses of the copolymerization suggested close reactivities of the double bonds between styrene and 1, whereas a rapid consumption of PDVB compared with styrene was observed in their copolymerization. The r₁, r₂,and r₁r₂ values for the copolymerization of styrene with 1 were determined to be 1.00, 1.09, and 1.09, respectively, which suggests that a more homogeneous network structure can be attained with 1. The living chain end of the produced living gel initiated the polymerization of tert‐butyl methacrylate to give an insoluble block copolymer in a good yield. The hydrolysis of the ester group of the block copolymer led to an amphiphilic copolymer that exhibited a characteristic property of a hydrogel. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2543–2547, 2000     

Free‐radical copolymerization of styrene with butyl acrylate. II. Elemental kinetic copolymerization step predictions from homopolymerization data

The free‐radical copolymerization of styrene and butyl acrylate has been carried out in benzene at 50 °C. The lumped k _p/k parameter (where k _p and k _t are the average copolymerization propagation and termination rate constants, respectively) has been determined. Applying the implicit penultimate unit model for the overall copolymerization propagation rate coefficient and the terminal unit effect for the overall copolymerization termination rate coefficient and using the homopolymerization kinetic coefficients, we have found good qualitative agreement between the experimental and theoretical k _p/k values. The variation of the copolymerization rate in solution with respect to the values previously found in bulk has been ascribed to a chain length effect on the copolymerization termination rate coefficient. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 130–136, 2004     

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.     

Free-radical polymerization of vinyl ferrocene

The results of quantitative studies of the rates of free-radical polymerization of vinyl ferrocene indicate that the latter has polymerization characteristics similar to those of styrene. The rates of homopolymerization of these two monomers in benzene at 70°C. were measured with the use of azobisisobutyronitrile as catalyst. The rate constants (k = R_p/[M][I]^1/2) are k_VF = (1.1 ? 1.8) × 10^?4, k_STY = 1.65 × 10^?4. Small amounts of vinyl ferrocene and styrene have similar effects on the rates of polymerizations of methyl methacrylate and ethyl acrylate and on the molecular weights of the resulting polymer. Polystyrene and poly(vinyl ferrocene) with similar molecular weights are isolated from polymerizations carried out under identical conditions. The rates of copolymerization of vinyl ferrocene—methyl methacrylate, vinyl ferrocene—styrene, and styrene—methyl methacrylate were determined by following the disappearance of monomers by means of gas chromatographic analyses. The relative reactivity for vinyl ferrocene is slightly lower than that for styrene.     

Copolymerization reactivity of poly(methyl methacrylate) macromer

Poly(methyl mehtacrylate)(PMMA) macromers with several vinyl groups at both chain ends were synthesized by the mechanical scission reaction of the main chain in the presence of p-divinylbenzene(p-DVB). The radical copolymerization of this macromer with styrene(St) or MMA was carried out in benzene at 60°C and the reactivity ratio of both monomers (r₂) was calculated from a kinetic scheme of copolymerization. As a result, the effect of molecular weight and concentration of macromers was not observed in both copolymerization systems. The value of r₂, however, decreased as the number of end vinyl groups in a macromer (N) increased. These results are discussed in some detail as we describe the construction of the kinetic model of copolymerization.     

Vinyl polymerization with a binary system of p‐chlorobenzenediazonium salt and sodium tetraphenylborate

A combined system of sodium tetraphenylborate (STPB) and p‐chlorobenzenediazonium tetrafluoroborate (CDF) serves as an effective initiator at low temperatures for acrylate monomers such as methyl methacrylate (MMA), ethyl acrylate, and di‐2‐ethylhexyl itaconate. The polymerization of MMA with the STPB/CDF system has been kinetically investigated in acetone. The polymerization shows a low overall activation energy of 60.3 kJ/mol. The polymerization rate (R_p) at 40 °C is given by R_p = k[STPB/CDF]^0.5[MMA]^1.6, when the molar ratio of STPB to CDF is kept constant at unity, suggesting that STPB and CDF form a complex with a large stability constant and play an important role in initiation and that MMA participates in the initiation process. From the results of a spin trapping study, p‐chlorophenyl and phenyl radicals are presumed to be generated in the polymerization system. A plausible initiation mechanism is proposed on the basis of kinetic and electron spin resonance results. A large solvent effect on the polymerization can be observed. The largest R_p value in dimethyl sulfoxide is 11 times the smallest value in N,N‐dimethylformamide. The copolymerization of MMA and styrene with the STPB/CDF system gives results somewhat different from those of conventional radical copolymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4206–4213, 2001     

Copolymerization of styrene and butadiene in emulsion. II. Relative rates of crosslinking and propagation

For the styrene–butadiene emulsion copolymerization (71 parts butadiene:29 parts styrene) the ratio of the rate coefficients for crosslinking, k_x, and propagation, k_p, have been determined at 5, 15, and 25°C by using an adaption of the method of Morton and co-workers. These ratios yield a value of 4.85 kcal/mole for the difference in activation energy between crosslinking and propagation, E_x ? E_p. Since the relative frequency of crosslinking and propagation depends upon the copolymer composition, and hence upon the free monomer ratio and the temperature, the range of application of these data is more limited than in a simple homopolymerization.     

COPOLYMERIZATION OF 1-OCTENE WITH STYRENE BY RARE EARTH COORDINATION CATALYSTS

The copolymerization of l-octene with styrene catalyzed by rare earth coordination catalysts has been studied for the first time. Some features and kinetic behavior are described. The overall activation energy of the copolymerization was 22.2 KJ/mol and the copolymerization rate could be expressed as R_p=K_p [Nd] [M]~2. (=1.68×10~(-3) L~2/mol~2. S, 50℃, [Oct]/[St]=1). The catalytic activity of various rare earth elements in Ln (naph)_3 for the copolymerization was compared and shows the following sequence: Dy, Y, Yb>Ho>Sm, Gd, Nd>Pr>Ce>La>Tm. Both monomers of l-octene and styrene in the copolymerization by Nd (naph)_3-AlEt_3 have the tendency of constant proportion copolymerization. The structure of the copolymers was studied by ~1H-NMR.     

Kinetics of Free Radical Copolymerization. V. Copolymerization of Ethyl Acrylate with Styrene. Composition of Copolymers

The composition of copolymers formed at 50°C in ethyl acrylate/ styrene/azo-bis-isobutyronitrile/benzene systems of different composition was investigated. The experimental composition data (based on the elementary analysis of copolymers) were evaluated by the η-ζ transformation method. Finite monomer conversions were taken into account. The classical composition equation was found to describe the system under investigation. The reactivity ratios are p ₁ = 0.152 ± 0.006; p ₂ = 0.787 ± 0.023. The free radical copolymerization of ethyl acrylate and styrene has been investigated in benzene solution at 50°C. Our results on the initiation kinetics were disclosed in our recent publication [1]. Now we are reporting on our studies concerning the composition of ethyl acrylate/styrene copolymers.     

Intramolecular cyclization of styrene–p-divinylbenzene copolymers

Styrene has been copolymerized at low conversion with minor quantities of p-divinyl-benzene (p-DVB) in (10–15%) solution in toluene and cyclohexane. Under these conditions the molecular weight of the polystyrene formed in the absence of p-DVB was controlled by chain transfer, and the copolymerization coefficients of the styrene and the p-DVB agreed with previous work. Polymer molecular weights were studied as a function of conversion. At very low conversions the number-average (2.2 × 10⁵) and the weight-average (4.4 × 10⁵) molecular weights were unaffected by substituting some of the styrene by p-DVB, but as the reaction continued M?_n increased slowly and M?_w much faster. On the other hand, even at the lowest conversions the intrinsic viscosity was drastically reduced by the introduction of p-DVB, and the radius of gyration, as measured by light scattering, fell. Infrared studies on the polymer show that the concentration of pendent double bonds in low-conversion copolymers is about half of the doubly substituted phenyl groups. It is concluded that the first polymer chains formed are extensively cyclized with the formation of a relatively large number of small rings.     

Retardation of radical polymerization by phenylacetylene and its p-substituted derivatives

Radical polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene and five of its p-substituted derivatives were carried out with the use of 2,2′-azobisisobutyronitrile as the initiator at 60°C. The initial overall rates of the polymerizations of styrene and methyl methacrylate in the presence of phenylacetylene were not proportional to the square root of the initiator concentration under the experimental conditions employed. The relationship between the overall polymerization rate and the concentration of the phenylacetylenes could be expressed by the Kice equation for the rate of a radical polymerization in the presence of a terminator. From this relationship the rate constant (k_s) of the reaction of a growing polymer radical with the phenylacetylenes and the constant C_s = (k_s/k_p), where k_p is the propagation rate constant of vinyl monomers, were determined. The C_s value thus obtained agree well with that derived from the relationship between the number-average degree of polymerization and the molar ratio of the phenylacetylenes to the vinyl monomer. Therefore the mechanism of the reaction may be considered as being one in which the growing radical reacts with the ethynyl group of the phenylacetylenes to yield a comparatively stable radical which terminates mainly by reaction with the growing radical, and so apparently the phenylacetylenes retard the vinyl polymerization. The substituent effects on the reaction were discussed on the basis of the following modified Hammett equation proposed by Yamamoto and Otsu: log [C_s(p-sub. PA)/C_s(PA)] = ρσ + γE_R where PA represents phenylacetylene, σ and E_R are the Hammett polar substituent constant and resonance substituent constant, respectively, and both ρ and γ are reaction constants. The γ value for the polymerization of both styrene and methyl methacrylate was 1.7. The ρ value was 1.0 for the polymerization of styrene and approximately zero for that of methyl methacrylate. These results demonstrate that the reactivity of the phenylacetylenes with the growing chain is influenced by both polar and resonance effects of their p-substituents in the degradative copolymerization of styrene and only by the resonance effect in that of methyl methacrylate.     

Isomeric effect of the Et(H4Ind)2Zr(CH3)2 catalyst on the copolymerization of ethylene and styrene: A computational study

A density functional theory (B3LYP) computational study of the ethylene–styrene copolymerization process using meso‐Et(H₄Ind)₂Zr(CH₃)₂ as the catalyst is presented. The monomer insertion barriers in meso species are evaluated and compared with previously obtained barriers in rac diastereoisomers. Differences related to ethylene homopolymerization and ethylene–styrene copolymerization activities as well as styrene incorporation into the copolymer are found between the meso and rac diastereoisomers. Nevertheless, a migratory insertion mechanism seems to hold for both diastereoisomeric species. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4752–4761, 2006     

Kinetics of polymerization of styrene-in-water microemulsions

The kinetics of polymerization of styrene-in-water microemulsions was investigated using dilatometry. From plots of percentage conversion versus time, the rate of polymerization, R _p, was determined. From log-log plots of R _p versus styrene and initiator [2,2′-azobis(isobutyronitrile), AIBN] concentrations the following relationship was established: R _p∝ [styrene]^1.2 [AIBN]^0.46. These exponents are similar to those predicted by the theory of emulsion polymerization. The results also showed a rapid conversion in the initial period (interval 1) followed by a slower rate at longer times (interval 2). It was suggested that in interval 1, the main process in nucleation of the microemulsion droplets, whereas in interval 2 propagation is the more dominant factor. The rapid polymerization of microemulsions is consistent with their structure, whereby very small droplets with flexible interfaces are produced. Received: 2 March 1999 Accepted in revised form: 10 May 1999