The structure of copolymers of vinyl cyclohexane with styrene

Copolymerization of vinyl cyclohexane (monomer-1) with styrene was investigated in the presence of the stereospecific complex catalyst TiCl₃ + Al(iso-C₄H₉)₃. Monomer reactivity ratios were r₁ = 0·177 ± 0·051 and r₂ = 2·117 ± 0·370. The monomer unit distributions in the copolymers were estimated by comparison of the i.r.-spectra of copolymers and the isotactic homopolymers using absorption bands at 565 and 1084 cm^?1 which correspond to the vibrations of styrene blocks containing ? 5 styrene units and the band at 985 cm^?1 characterizing polystyrene crystallinity. The data indicate the tendency towards alternation in the copolymerization. Analysis of the experimental and literature data led to the conclusion that distribution of the units in copolymers of vinyl cyclohexane with α-olefins is determined by the nature of the α-olefin. The following activity series is proposed for α-olefins in their copolymerization with vinyl cyclohexane in the presence of catalytic systems based on titanium salts and organo-aluminium compounds: propylene >; 4-methylpentene-1 >; styrene >; 3-methylbutene-1 ～ vinyl cyclohexane.     

Radiation-induced copolymerization of tetrafluoroethylene with vinyl ethers

Radiation-induced copolymerization of tetrafluoroethylene with various vinyl ethers has been studied. It was found that tetrafluoroethylene can be copolymerized with vinyl ethers to give alternating copolymers over a wide range of the initial monomer concentration in the monomer mixture. The monomer reactivity ratios were determined for the copolymerization of tetrafluoroethylene with n-butyl vinyl ether as 0.005 (r_TFE) and 0.0015 (r_NBVE). The rate of copolymerization is extremely high and has a maximum at an equimolar concentration of two monomers. The alternating structure of the copolymers was confirmed by the analysis of NMR spectra. Some thermal properties of the copolymers were measured by DSC and DTA.     

New information on the alternating copolymerization of butadiene-1,3 with acrylonitrile

Butadiene-1,3 and acrylonitrile were copolymerized by alkylaluminum halides alone or, more effectively, by the alkylaluminum halide/vanadium compound systems, into an alternating copolymer in which the butadiene units are linked predominantly in the trans-1,4 configuration. The efficiency of the aluminum components in the latter catalyst systems appear to decrease in the following order: AlEtCl₂ > Al₂Et₃Cl₃ ? AlEt₂Cl(?AlCl₃). The alkylaluminum halides could also be used effectually in the form of the complex with acrylonitrile. The catalytic activity was markedly affected by the order of mixing of the catalyst components and the monomers. Effective catalysts could be prepared only when the catalyst components were mixed in the presence of acrylonitrile. The catalyst activity was also found to depend upon the Al/V ratio, reaching its maximum when the ratio was about 20 in the AlEtCl₂·AN/VO(Ot-Bu)₃ system. Other combinations of conjugated diene with conjugated polar vinyl monomer were similarly copolymerized by these catalysts. It was found that different feed ratios between the diene and the vinyl monomer which were varied over a wide range always resulted in the formation of a 1:1 copolymer. The butadiene-acrylonitrile copolymer thus formed gave an NMR spectrum in which there was only one peak assignable to the methylene protons (7.72 τ) of the butadiene unit. On the basis of these findings, it may be suggested that alternating copolymerization prevails in the polymerization systems here investigated.     

Activity of diallylamido-bis(diethylamido)guanidinium chloride in radical polymerization reactions

The activity of diallylamido-bis(diethylamido)guanidinium chloride in radical polymerization and copolymerization with vinyl monomers giving rise to random copolymers has been studied. A lower activity of diallylamido-bis(diethylamido)guanidinium chloride than that of vinyl monomers has been demonstrated. It has been shown that this monomer readily copolymerizes with sulfur dioxide and alternating copolymers of equimolar composition are formed regardless of the comonomer ratio in the initial mixture and the reaction conditions (the nature of solvent and initiator, temperature, and conversion). The structure of polymers has been studied by ¹³C NMR spectroscopy.     

Donor–acceptor complexes in copolymerization. XLIX. Cationic polymerization of donor monomers in presence of polar solvents and acrylic monomers. A revised mechanism for polymerization of comonomer complexes

α-Methylstyrene (MS) and isobutyl vinyl ether (VE) readily polymerize, styrene (S) polymerizes to a small extent, and isobutylene (IB), butadiene (BD), and isoprene (IP) fail to polymerize in the presence of catalytic amounts of AlCl₃ when propionitrile, ethyl propionate, and methyl isobutyrate are used as reaction media. MS polymerizes readily and S polymerizes with difficulty in the presence of AlCl₃ to yield homopolymers when acrylonitrile (AN) is present and copolymers with ethyl acrylate (EA) and methyl methacrylate (MMA). VE readily homopolymerizes, while IB, BD, and IP fail to polymerize in the presence of AlCl₃ and the acrylic monomers. VE readily homopolymerizes, S and MS polymerize to a very small extent, and IB, BD, and IP do not polymerize in the presence of ethylaluminum sesquichloride (EASC) in polar solvents. VE readily homopolymerizes in the presence of EASC and the acrylic monomers. MS polymerizes to a small extent in the presence of EASC and the acrylic monomers to yield equimolar copolymers with EA and MMA and a mixture of cationic homopolymer and equimolar copolymer with AN. S yields equimolar copolymers in low yield in the presence of EASC and the acrylic monomers. IB, BD, and IP in the presence of EASC do not polymerize to any significant extent when EA is present, form AN-rich copolymers and yield poly(methyl methacrylate) in the presence of MMA. A revised mechanism is presented for the formation of cationic, radical, random, and alternating copolymers as well as alternating copolymer graft copolymers in the copolymerization of donor and acceptor monomers.     

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.     

High Tg microspheres by dispersion copolymerization of N‐phenylmaleimide with styrenic or alkyl vinyl ether monomers

Solution and dispersion copolymerizations of N‐phenylmaleimide (PMI) with either styrenics or alkyl vinyl ethers (AVEs), systems with a tendency to give alternating polymers, were investigated with the goal of producing high glass transition particles. Equimolar solution copolymerization of PMI with styrenics gave alternating copolymers, whereas AVEs gave PMI‐rich copolymers (～65:35) except for t‐butyl vinyl ether, which gave copolymers with only a slight excess of PMI. These copolymers had glass transition temperatures (T_gs) ranging from 115 to 225 °C depending on comonomer(s). Dispersion copolymerization in ethanol‐based solvents in the presence of poly(vinylpyrrolidone) as steric stabilizer led to narrow‐disperse microspheres for many copolymers studied. Dispersion copolymeriations of PMI with styrenics required good cosolvents such as acetonitrile or methyl ethyl ketone as plasticizers during particle initiation and growth. Dispersion copolymerizations generally resulted in copolymer particles with compositions and T_gs very similar to those of the corresponding copolymers formed by solution polymerization, with the exception of t‐butyl vinyl ether (tBVE), which now behaved like the other AVEs. Dispersion terpolymerizations of PMI (50 mol %) with different ratios of either n‐butylstyrene and t‐butylstyrene or n‐butyl vinyl ether and tBVE led to polymer particles with T_gs that depended on the ratio of the two butyl monomers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Copolymerization of methyl acrylate and vinyl acetate catalyzed by ethylaluminium chlorides

The copolymerization of vinyl acetate with methyl acrylate in the presence of Et₂AlCl, Et_1.5AlCl_1.5, and Et₂AlCl-benzoyl peroxide systems has been investigated. The influence of monomer ratios and organoaluminium compound concentration on the copolymer yield and composition have been determined and discussed. The monomer sequences distribution has been studied by means of ¹³C-NMR. It was found that organoaluminium compounds in the studied systems catalyze not only the alternating copolymerization, but also the homopropagation of both monomers. An alternating copolymer was obtained in reactions carried out at ?78°C, when a large excess of vinyl acetate was used in the monomer feed.     

Copolymerization of 2,3-Dihydropyran and Ethyl Vinyl Ether with Maleic Anhydride

2,3-Dihydropyran (DHP) and ethyl vinyl ether (EVE) were co-polymerized with maleic anhydride (MA) with benzoyl peroxide at 60°C, and 1:1 alternating copolymers were obtained. The rates were maximum at 1:1 monomer composition. Spontaneous copolymerization and solvent effect on the rate were observed in the copolymerization of DHP with MA, in which initial rates were slower in more polar solvents. Participation of charge transfer complex was considered. EVE copolymerized rapidly with MA, reaching the theoretical limiting conversion of 1:1 alternating copolymerization. Although DHP-MA comonomer pair and EVE-MA comonomer pair formed similar 1:1 charge transfer complexes, DHP copolymerized slowly with MA to produce a low molecular weight copolymer, and the limiting conversion was much lower than the theoretical one. To explain these, degradative chain transfer to DHP monomer is proposed as the initial rate of DHP-MA copolymerization is proportional to the initiator concentration to the power 1.1. Q and e values of DHP were calculated to be 0.013 and -0.93, respectively, from the monomer reactivity ratios of copolymerization of DHP with acrylonitrile [r₁ (DHP)=0.003 ± 0.006 and r₂ (AN)=3.6 ± 0.3].     

Copolymerization of Chloroprene with Methyl Methacrylate by the EtnAICI3.n (n=1, 1.5, 2)-Vanadium Compound System

Abstract

The copolymerization of chloroprene with methyl methacrylate was studied in the presence of Et_n A1C1_3-n (n=1, 1.5, 2)-vanadium compounds. Monomer reactivity ratios in various catalyst concentrations were compared with that of a usual radical initiator. The apparent monomer reactivity ratio changed with the concentration of alkylaluminum halide. In this polymerization, alternating copolymer could not be prepared by the ordinary catalyst concentration by which the alternating copolymerization of chloroprene with acrylonitrile was carried out. The addition of more than 10 mole % of the alkylaluminum halide based on two monomers was required to prepare the copolymer which had equimolar composition irrespective of the feed monomer ratio.

The configuration in the repeating unit of the copolymer was discussed by comparison with the NMR and IR spectra of the radical copolymer and the cyclic Diels-Alder adduct of chloroprene-methyl methacrylate. The high alternating tendency was clarified by ozonolysis of the copolymer which was prepared under the conditions which produced equimolar copolymer in various feed monomer ratios. The chloroprene unit of the copolymer was present in the 1, 4-trans structure in the copolymer prepared by the Et_n A1C1_3-n -vanadium compound system.     

Radical copolymerization of 3-tri-n-butylstannylstyrene with several vinyl monomers

The free radical homopolymerization and copolymerization of 3-tri-n-butylstannylstyrene (3-BTS) with styrene (ST), ethyl acrylate (EA), methyl methacrylate (MMA), vinyl acetate (VA), and acrylonitrile (AN) were carried out using 2,2′-azobisisobutyronitrile (AIBN) at 60°C. It was found that the yield of conversion to poly(3-BTS) increased with the molar ratio of initiator to monomer as well as with polymerization time. The conversion at equilibrium after 50 h was about 40%. The compositions of copolymer samples were determined from elemental analyses. Monomer reactivity ratio and Q-e values were calculated. The copolymers of 3-BTS-MMA and 3-BTS-AN were found to be alternating. The copolymers of 3-BTS with MMA, EA and AN were not soluble in any of a large number of organic solvents tested. The insolubility is believed to be due to formation of intermolecular coordination among the tributylstannyl moiety and the carbonyl or cyano groups of the polymer. These copolymers, however, were “soluble” in trihaloacetic acid, but this solubility was due to a cleavage of the trialkyltin moiety from the phenyl groups. The glass temperatures, T_g, and melting temperatures T_m, of the various polymers were also studied.     

Alternating copolymerization through the complexes of conjugated vinyl monomers–alkylaluminum halides

A vinyl monomer that has the nitrile or carbonyl group conjugated to the C?C double bond, such as acrylonitrile, methyl acrylate, and methyl methacrylate, forms a complex with an alkylaluminum halide, and the complex reacts spontaneously with a hydrocarbon monomer such as styrene, propylene, or ethylene, giving a high molecular weight copolymer. The copolymers always contain the two monomer units in 1:1 ratio. Thus styrene, copolymerized with methyl acrylate or methyl methacrylate in the presence of ethylaluminum sesquichloride in homogeneous toluene solution, gives such an equimolar copolymer regardless of the initial monomer compositions. The NMR spectra of these copolymers are distinctly different from those of the equimolar copolymers obtained with azobisisobutyronitrile as initiator and have simpler and well separated patterns. The copolymers and the corresponding radical copolymers appear to be amorphous, judged by their x-ray diffraction patterns and their differential thermal analyses. Their infrared spectra resemble each other very closely. Hence, the difference in the NMR spectra may be ascribed to the matter of the sequence distribution. The infrared spectrum of ethylene–methyl acrylate copolymer shows no absorption near 720 cm.^?1 due to the methylene sequence arising from ethylene–ethylene linkage. These experimental data lead to the inference that the equimolar copolymers obtained in this work may have an alternating sequence.     

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.     

Proposed Participation of Excited Monomer in the Free Radical-Catalyzed High Pressure,High Temperature Polymerization of Ethylene

The radiation-induced copolymerization of ethyl vinyl ether with dibutyl maleate was investigated over a wide range of comonomer compositions, dose rates, and in the temperature range from ?25 to 75° C. Both the rates of copolymerization and the molecular weights of the resulting copolymers were found to depend strongly on the initial comonomer composition, both reaching a maximum value at an equimolar comonomer composition. A copolymer was obtained in which the co-monomers alternate with regularity along the polymer chain over the entire range of comonomer compositions investigated. The monomer reactivity ratios were determined and found to be practically zero. The apparent activation energy was found to change at 35° C, the boiling point of the ethyl vinyl ether, from a value of 10.48 kJ/mole to a value of 18.86 kJ/mole above this temperature. This phase change also resulted in a marked decrease in the molecular weights of the copolymers formed above 35° C. The dose-rate dependence of the rate of copolymerization was found to be 0.70 over the dose-rate range     

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.     

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.     

Copolymers of vinyl and vinylidene chlorides with alkyl acrylates

High-molecular-weight copolymers of vinyl chloride and ethyl or butyl acrylate were prepared in high conversion and yield in the presence of boron trifluoride as the acrylate ester complexing agent. When the vinyl chloride monomer is in excess of equimolar amounts, the resulting copolymers are alternating; and when the alkyl acrylates are in excess, acrylate-rich copolymers are obtained. Ethylene–vinyl chloride–ethyl acrylate and propylene–vinyl chloride–ethyl acrylate terpolymers were also obtained with an ethyl acrylate content of 50 mole %. The relative reactivities of propylene, vinyl chloride, and ethylene in these polymerizations were 5.4, 3.8, and 1.0, respectively. Vinylidene chloride–ethyl acrylate copolymers that are nearly alternating and rich in acrylate or in vinylidene chloride have also been prepared. The monomer reactivity ratios for vinylidene chloride and ethyl acrylate in the presence of boron trifluoride are considerably lower than in its absence.     

Complexed copolymerization of vinyl compounds with alkylaluminum halides

The monomer reactivity in the complexed copolymerization of vinyl compounds with alkylaluminum halides has been extensively surveyed. Equimolar copolymers were obtained in various combinations of monomers which are classified into two monomer groups, A and B. The group B monomers are conjugated vinyl compounds having nitrile or carbonyl groups in the conjugated position and form complexes with alkylaluminum halides. The group A monomers are donor monomers having low values, such as olefins, haloolefins, dienes, and unsaturated esters. These A monomers belong to the same group of monomers which give alternating copolymers in conventional radical copolymerization with maleic anhydride, SO₂, and so on. In addition the complexed copolymerization has the same specific characteristics as the conventional alternating copolymerization, i.e., high reactivities of allyl-resonance monomers and inner olefins and no transfer of halogen atom to the copolymers in CCl₄. These features suggest little or no participation of the A monomer radical. The Q-e scheme is also discussed in terms of the monomer reactivity. More than two monomers selected from groups A and B give multicomponent copolymers in which alternating sequential structures hold with respect to A and B. Anomalous mutual reactivities between two B monomers in the terpolymerization were observed and indicate that the nature of radical in the complexed copolymerization may be different from that expected by the Lewis-Mayo equation. The complexed radical mechanism previously proposed is discussed in connection with the specific behavior mentioned above.     

Donor-Acceptor Complexes in Copolymerization. XVII. NMR Analyses of Random and Alternating Styrene–α-Chloroacrylonitrile Copolymers

The NMR spectra of random and equimolar alternating copolymers of styrene with a-chloroacrylonitrile were studied. The monomer sequence distribution in the random copolymers, prepared in the presence of free radical catalysts, as determined from NMR analyses, was in accordance with the values expected from the r₁ and r₂ values derived from the conventional copolymerization theory. The alternating structure of the copolymer prepared by complexation with AlEt_1-5 Cl_1-5 was confirmed. The equimolar random copolymer, prepared by free radical initiation, was shown to contain essentially alternating sequences.     

Radical alternating copolymerization of vinyl ethers

New alternating equimolar copolymers of electrophilic trisubstituted ethylenes, methyl 3-phenyl-2-cyanopropenoate and 2-phenyl-1,1-dicyanoethene, with ethyl, n-butyl, i-butyl, t-butyl, 2-chloroethyl, and phenyl vinyl ethers were prepared by free radical initiation. Chemical compositions of the copolymers are 1 : 1 in broad ranges of monomer ratios. The copolymerization rate of both electrophilic monomers with the vinyl ethers increase in the series 2-chloroethyl > ethyl > phenyl > n-butyl > i-butyl > t-butyl. These variations in the reactivity of the vinyl ethers are discussed in terms of their preferred conformations in donor-acceptor complexes with electrophilic trisubstituted ethylenes. © 1993 John Wiley & Sons, Inc.