Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. II. Properties of acrylonitrile–styrene copolymer

The properties of the acrylonitrile–styrene copolymer prepared in the presence of zinc chloride were investigated in comparison with those of a copolymer having the same overall composition and prepared by the ordinary radical procedure. The characteristics of the polymer prepared with ZnCl₂ were as follows: (1) less coloration by alkali treatment, (2) less coloration by thermal treatment and (3) higher glass transition temperature. These features may be attributed principally to the structure of the copolymer, which has more unlike bonds and less long sequences as described in the first article of this series. The effects of residual salt in the copolymer on the properties were also investigated.     

Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. III. NMR study of methyl methacrylate–styrene copolymer

The copolymer composition curve of the methyl methacrylate–styrene copolymer obtained by the copolymerization in the presence of ZnCl₂ has more alternating tendency than that of ordinary methyl methacrylate–styrene copolymer obtained by radical copolymerization. The fine structure of the copolymer was examined by NMR, and the mechanism of the propagation step of the copolymerization in the presence of ZnCl₂, which was proposed in the first report of this series, was verified.     

Dispersion copolymerization of styrene and other vinyl monomers in polar solvents

Dispersion polymerization is a very attractive method for preparing micrometer‐size monodisperse polymer particles. The applications of microspheres have been greatly expanded by the use of copolymers. Here, the dispersion copolymerization of styrene and seven other vinyl monomers was carried out in polar solvents. The effect of the different comonomers on the particle size was systematically investigated. The particle size first decreased and then increased with an increasing fraction of acrylamide in the monomer feed, and at a higher fraction of such a comonomer, only a gel‐like polymer was obtained. The particle size also increased with the increase in the contents of the hydrophilic comonomers in the monomer mixtures, and the copolymer molecular weight decreased meanwhile. Although the amount of the hydrophobic comonomer in the monomer mixture changed, the particle size was hardly affected. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 555–561, 2001     

Spontaneous copolymerization of 1,3-cycloheptadiene with acrylonitrile in the presence of zinc chloride

The reaction of 1,3-cycloheptadiene (1,3-CHpD) with acrylonitrile (AN) in the presence of ZnCl₂ leads spontaneously to the simultaneous formation of an alternating copolymer and a small amount of cycloadduct. The copolymer has a predominantly cis-1,4-structure. The formation of the charge—transfer complex between 1,3-CHpD and (AN)c (AN coordinated to ZnCl₂) in AN was detected by ultraviolet (UV) spectroscopy. The activation energies for the cycloaddition and for the copolymerization under the conditions used were determined to be 17.6 (in the presence of 1,1-diphenyl-2-picrylhydrazyl) and 16.3 kcal/mole, respectively. The rate of copolymerization in AN was found to depend on the 1.5th power of the concentrations of (AN)c and of 1,3-CHpD. Oxygen and UV irradiation causes an acceleration of the copolymerization only. On the basis of these results the mechanism of the spontaneous copolymerization is discussed and its relation to the cycloaddition in systems of 1,3-cyclodienes and AN in the presence of ZnCl₂ is mentioned.     

Alternating copolymer of styrene–acrylonitrile obtained with vanadium-based complex catalyst in presence of monomers

Vanadium-based catalyst complexes prepared in the presence of monomers have been used for the copolymerization of styrene and acrylonitrile. VOCl₃–Al(i-C₄H₉)₃ catalyst system seems to yield an alternating copolymer. The copolymers are easily soluble in DMF and have low softening points.     

Spontaneous copolymerization of 1,3-cyclohexadiene with polar vinyl monomers

In the reactions of 1,3-cyclohexadiene(1,3-CHD) with polar vinyl monomers, CH₂?C(X)Y (X is -? CN and ? CO₂CH₃; Y is ? CI, ? H, and ? CH₃), the two α-chlorosubstituted monomers underwent rapid spontaneous copolymerization, accompanied by the formation of a small amount of cycloadduct. Both polar monomers also gave predominantly copolymers in the reaction with 1,3-cycloheptadiene(1,3-CHpD) in lower yield. 1,3-Cyclooctadiene (1,3-COD) reacted only with α-chloroacrylonitrile (CAN) to give a copolymer, while only cycloaddition took place in systems involving cyclopentadiene(CPD) as diene. The charge–transfer (CT) complex formation of 1,3-CHD with CAN and methyl α-chloroacrylate(MCA) was confirmed by ultraviolet spectroscopic studies and the equilibrium constants estimated were 0.18 and 0.07 liter/mole, respectively, at 25°C in chloroform as solvent. The activation energies for the copolymerizations of 1,3-CHD with CAN and MCA in benzene were determined to be ca. 6.6 and 9.6 kcal/mole, respectively. In the system composed of 1,3-CHD and CAN, only the copolymerization was affected by solvents used and oxygen. Although addition of ZnCl₂ to the system resulted in the acceleration of the both reactions, the variation in the product ratio of copolymer to cycloadduct with ZnCl₂ concentration showed a maximum. Based on the results in the present and preceding studies for systems involving 1,3-cyclodienes and acceptor monomers, the relationship between the cycloaddition and the spontaneous copolymerization is discussed.     

Polymerization of coordinated monomers. XII. Alternating copolymerization of γ-crotonolactone with styrene with the use of stannic chloride

γ-Crotonolactone and styrene copolymerize alternately in the presence of stannic chloride at -10°C under photoirradiation. The intrinsic viscosity of the resulting copolymer is in the range of 0.6–0.8 dl/g at 30°C in chloroform. The equilibrium constants for the complex formation between stannic chloride and γ-crotonolactone were determined in 1,2-dichloroethane-toluene solution at 0 and ?20°C by use of absorption band at 350 nm. Continuous variation plots based on the ¹H-chemical shift show a 1:1 interaction between styrene and the γ-crotonolactone coordinated to stannic chloride. The equilibrium constants for the ternary molecular complex formation between the coordinated γ-crotonolactone and styrene were determined in 1,2-dichloroethane in the temperature range from ?20 to 0°C. The equilibrium constants, derived independently from the measurements of the nonequivalent protons in γ-crotonolactone, are equal to each other within the experimental error. The mechanism of the alternating copolymerization of γ-crotonolactone and styrene in the presence of stannic chloride is discussed in terms of the homopolymerization of the ternary molecular complex.     

Free radical copolymerization in the presence of lewis acids. I. Alternating copolymerization of vinyl acetate with acrylic acid in the presence of GeCl4 and BCl3

Alternating copolymers of vinyl acetate (VAC) and acrylic acid (AA) were obtained by free radical polymerization in the presence of GeCl₄ and BCl₃. For the GeCl₄ system, the reaction rate was proportional to [initiator]^1/2. Optimum rate was obtained when the molar ratio of the monomers was 1:1. The chain transfer agent CCl₄ had no effect on the reaction. By means of ultra-violet spectra analysis, it was concluded that both VAC and AA formed complexes with GeCl₄. ESR analysis gave us the information that salt complexed acrylic acid radical had greater cationic characteristics than uncomplexed radical. Thus the nature of alternation may be due to both complexed AA radical and activated monomer complexes.     

Polymerization of complexed monomers. I. Alternating copolymers from cyclopentene and complexed polar monomers

Alternating equimolar copolymers of cyclopentene with acrylonitrile and methyl acrylate were prepared in the presence of ethylaluminum sesquichloride. Varying conditions of monomer ratio, temperature, light, and reaction time were studied. The structures of the polymers and mechanistic implications are discussed.     

Alternating copolymerization of isoprene and butadiene with acrylonitrile

Copolymerizations of acrylonitrile and isoprene or butadiene were carried out in the presence of a new catalytic system containing Cr(O-tert-Bu)₄ and AlEtCl₂. It was found that the copolymer compositions have a highly alternating structure, even with varying feed ratios of monomer. The nuclear magnetic resonance spectra of the copolymers obtained with this catalytic system were observed and are discussed in terms of the alternation.     

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.     

Alternating copolymerization of benzofuran and acrylic monomers in the presence of organoaluminum compounds

The copolymerization of benzofuran and acrylic monomers, such as acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate, was investigated in the presence of aluminum compounds as complexing agents for acrylic monomers. Among the various kinds of aluminum compound, ethylaluminum sesquichloride is the most suitable for alternating copolymerization, whereas ethoxyaluminum compounds of low acidity allow the incorporation of excess acrylic monomer and dichloride of strong acidity is likely to induce cationic homopolymerization of benzofuran as a side reaction. The equimolar amount of sesquichloride with respect to acrylic monomer is necessary for alternating copolymerization. Azobisisobutylonitrile (AIBN) is an effective initiator but benzoyl peroxide is not. Nuclear magnetic resonance (NMR) of the copolymer indicates that the copolymer is essentially alternating, although some block sequences of acrylic monomer sometimes exist. As a mechanism the copolymerization via a ternary complex of acrylic monomer, aluminum compound, and benzofuran is considered. Free acrylic monomer participates in copolymerization when the amount or acidity of the complexing agent is insufficient. A quantitative relation between monomer and copolymer composition is derived from a scheme based on the copolymerization of the donor monomer-acceptor monomer complex with free acrylic monomer.     

Polymerization of coordinated monomers. XVII. Alternating copolymerization of methyl methacrylate with styrene by boron compounds

By the use of various boron compounds methyl methacrylate and styrene were copolymerized under photoirradiations at ?20°C. The alternately regulating activities of the boron compounds in the copolymerizations were in the following order: boron trichloride > ethylboron dichloride > boron trifluoride > diethylboron chloride ? triethylboron (?0). Boron trichloride and ethylboron dichloride exhibited such high regulating activities that their presence in 1 mol% in the charged methyl methacrylate was sufficient to complete equimolar alternating copolymerization. The alternating copolymerization proceeded in the steady state. The copolymerization rates decreased in the following order: boron trichloride ? ethylboron dichloride > diethylboron chloride ? triethylboron (?0). The cotacticities of methyl methacrylate-centered triads in the resulting copolymers were identical to those prepared with boron trichloride, ethylboron dichloride, and diethylboron chloride. The mechanism of the alternating copolymerization is discussed.     

Miscibility of poly(vinyl chloride) with styrene/acrylonitrile copolymers

Poly(vinyl chloride) (PVC) is shown to be miscible with styrene/acrylonitrile copolymers (SAN) having AN compositions from 11.5 to 26%. Blend samples were prepared using several methods, including solution casting, melt mixing, and precipitation of solutions by a nonsolvent. It is shown that the blend phase behavior is affected by preparation method due to the solvent effect, or Δ_χ effect, and lower critical solution temperature (LCST) behavior. The intramolecular repulsion between styrene and acrylonitrile units in SAN is shown to be the cause of miscibility using heats of mixing obtained from low-molecular-weight analog compounds. An FTIR analysis supplements the above results.     

Structure-reactivity relations of conjugated and unconjugated monomers: Acrylates and methyl vinyl ketone in copolymerization with styrene compared with vinyl esters in copolymerization with ethylene

This article describes the copolymerization of methyl vinyl ketone (MVK), methyl acrylate (MA), and methyl methacrylate (MMA) with styrene (St) as reference monomer at 3.4 MPa and 335 K with toluene as solvent. In addition, the effect of pressure on the binary copolymerizations of St-Ma-MMA is discussed. It appearsthat in case of conjugated monomers reactivity decreases as the electron-donating character of the substituents increases, whereas the reverse is found in unconjugated monomers. This is explained by the finding that in conjugated monomers resonance effects induced by polar factors play a dominant role, whereas in unconjugated monomers mainly polar factors are governing the relative reactivities. The r values at 3.4 MPa are compared with those predicted by means of the Q-e scheme and Patterns. No definite conclusions could be drawn about the applicability and validity of either scheme, although Patterns shows excellent result in case of the H function of Mayo. In vinyl ester copolymerizations and Le Noble and Asano's example of the menshutkin reaction one single factor (polarity and steric hindrance, successively) dominates ΔG#, ΔG and ΔV#. This allows a straight forward interpretation of the result with the Hammond postulate and is in full agreement with Evan's potential-energy calculations. In conjugated monomers, however, an interplay of reasonance and polar factors is found. The general validity of these findings needs further experimental and theoretical support.     

Alternating copolymerizations of styrene and acrylic monomers initiated with carbanions in the presence of ZnCl2

On electrochemical initiation of alternating copolymerizations of styrene–acrylonitrile (AN) and styrene–diethyl fumarate (DEF) in the presence of ZnCl₂, radical anions of AN–ZnCl₂ and DEF–ZnCl₂ complexes produced at the cathode were assumed to initiate copolymerization. In analogy with the cathode-initiated copolymerization, the radical anions of AN–ZnCl₂ and DEF–ZnCl₂, generated with the carbanions such as sodium naphthalene, disodium α-methylstyrene tetramer dianion, and butyllithium, were also found to produce alternating copolymers of styrene–AN and styrene–DEF. On the contrary, no polymers were obtained from methyl methacrylate (MMA)–styrene and methacrylonitrile (MAN)–styrene in the presence of ZnCl₂ either with carbanions or by electrochemical reduction. Styrene–MAN–ZnCl₂ yielded an alternating copolymer with carbanions upon introduction of oxygen.     

Free-Radical copolymerization of N-vinylsuccinimide with butyl acrylate in the presence of zinc chloride and aluminum chloride

The free-radical copolymerization of N-vinylsuccinimide with butyl acrylate performed in dimethyl sulfoxide and benzyl alcohol in the presence of zinc chloride and aluminum chloride as complexing agents is studied. Under the given conditions, the reactivity ratios are determined. It is shown that zinc chloride influences the electron-density distribution only in butyl acrylate molecules. It is found that benzyl alcohol retards the total rate of polymerization. The character of the monomer-unit distribution in copolymer macromolecules is described.     

Alternating copolymerization of styrene and methyl α-chloroacrylate with diethylaluminum chloride

The alternating copolymerization of styrene and methyl α-chloroacrylate (MCA) with diethylaluminum chloride (Et₂AlCl) in benzene at 0°C has been investigated. The copolymer has an equimolar composition irrespective of the feed monomer composition, the copolymer yield and the amount of Et₂AlCl used. The copolymerization proceeds first very rapidly and then rather slowly after attaining a certain yield which varies proportionally to the amount of Et₂AlCl used. A maximum copolymer yield is observed at about 60% MCA feed composition. The ¹H-NMR analyses of dyad, triad, and pentad of the alternating deuterated α-d-St-MCA copolymer indicate that the configuration of this copolymer can be explained by a single parameter, coisotacticity σ(σ = 0.69). A favorable mechanism of the alternating propagation as well as of the stereoregularity control is discussed.     

Copolymerizations mechanochemically initiated—I. Influence of some factors on the copolymerization of acrylonitrile with styrene

The possibility of initiating copolymerization mechanochemically is studied. Acrylonitrile and styrene were used as monomers; the mechanical energy was supplied by vibratory milling in metallic equipment. No additives were introduced to activate the reaction. The process was carried out at 18 ± 2° and study was made of the following parameters: duration, rate of wear of the grinding media, comonomer ratio. The reaction probably proceeds through radical-anions and catalysis by the apparatus walls. The copolymers thus synthesized are crystalline, thermostable compounds resistant to chemical agents.     

Copolymerization of vinyl ketones with allylbenzene in the presence of zinc chloride

Copolymerization of 3-buten-2-one (MVK) and 3-methyl-3-buten-2-one (MIPK) with allylbenzene (AB) in the presence of zinc chloride (ZnCl₂) was studied. The apparent monomer reactivity ratio decreased with an increasing concentration of ZnCl₂ added. By assuming a terpolymerization system as free vinyl ketone (M₁), vinyl ketone complexed with ZnCl₂ (M₂), and AB(M₃), the absolute monomer reactivity ratios were determined by using the least squares method: k₁₁/k₁₂ = 0.0038, k₁₁/k₁₃ = 11.77, k₂₂/k₂₁ = 1.37, and k₂₂/k₂₃ = 3.77 for the MVK-AB system, and k₁₁/k₁₂ = 0.0070, k₁₁/k₁₃ = 55.47, k₂₂/k₂₁ = 1.84, and k₂₂/k₂₃ = 11.16 for the MIPK-AB system, respectively. It is seen from these values that the complexed vinyl ketones are more reactive to both polymer radicals which have free and complexed vinyl ketone units at its terminal position than the free vinyl ketones. Q and e values for MVK and MIPK complexed with ZnCl₂ were found to be Q = 850, ^e_(MVK)2ZnCl₂ = 2.97, Q = 2.62, respectively.