Propagation Mechanism of Radical Copolymerization of Sulfur Dioxide and Vinyl Chloride

Radical copolymerization of sulfur dioxide and vinyl chloride (VC) has been studied by the comparison of the composition of copolymers obtaining from different reaction conditions, i.e., reaction temperatures, feed compositions, and total monomer concentrations. The composition of VC in copolymer is independent of comonomer composition except at high concentration of VC in feed; it increases with increasing reaction temperature or decreasing total monomer concentration. At lower temperature, the composition of copolymer becomes independent of total monomer concentration. The overall rate of polymerization is proportional to [VC]^1,7 and [SO₂]^0.5. These results were compared with those obtained in our previous study on the SO₂-styrene copolymerization. A propagation mechanism for radical copolymerization of SO₂ and VC is also proposed.     

Copolymerization of Vinyl Chloride and Sulfur Dioxide. III. Evaluation of the Copolymerization Mechanism

The mechanism of copolymerization of vinyl chloride (V) with sulfur dioxide (S) to form a variable composition polysulfone with average V:S molar ratio n ≥ 1 is examined. The copolymerization deviates from Lewis-Mayo behavior above -78°C. Alternative models for propagation involving (1) penultimate and pen-penultimate unit effects, (2) complex participation, and (3) depropagation are considered quantitatively by comparison of calculated and experimental copolymer/comonomer composition relationships and comonomer sequence distributions. Our theoretical modeling of the copolymerization shows that it is difficult to discriminate convincingly between alternative mechanisms. The penultimate and pen-penultimate effect models can account for the copolymer compositions, but not for the dilution effects which were observed provided the diluent is truly inert. The complex participation model can account for experimental behavior from -78 to -18°C by the assumption of addition of SV complexes, but it becomes rapidly less satisfactory at higher temperatures. Depropagation is the only model which can account for the compositions and dilution effects above 0°C. Progressive depropagation, with increasing temperature, of chains ending in the triad sequences ～SVS?, ～VVS?, and ～VSV? can explain the observed behavior over the entire comonomer composition and temperature range, but involvement of comonomer complexes in the propagation reactions is highly likely below 0°C.     

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.     

Vinyl Chloride-Vinyl Bromide Copolymers

Abstract

Radical copolymerization kinetics of vinyl chloride (VC) and vinyl bromide (VB) lead to the following reactivity ratios r_VC=0.825 r_VB=1.05 Vinyl bromide acts as a chain transfer agent, more powerful than vinyl chloride, the transfer constant for VC radicals being 8.5 × 10^?3 at 40° C. Neither thermal nor ionic degrad-ation produce controlled distribution of short diene sequences in the copolymer. In the ionic process initiated with LiCl or LiBr in dimethylformamide solution, substitution of halogen atoms as well as acid elimination takes place.     

Copolymerization of vinyl chloride with sulphur dioxide—I molecular association between vinyl chloride and sulphur dioxide

The formation of VC-SO₂ and VC-(SO₂)₂ complexes in liquid mixtures of vinyl chloride (VC) and sulphur dioxide has been shown by (a) the freezing point composition diagram and (b) chemical shifts in the PMR spectrum of VC over the complete composition range. It is postulated that SO₂ can associate with the CC bond and the Cl atom. These complexes may be involved in the copolymerization and influence the composition and stereochemistry of the product. PMR spectra of VC-SO₂-ethane(E) mixtures with [SO₂] ? [E] ? [VC] gave K_v = 2·0 ± 0·5, 1·5 ± 0·1 and 1·1 ± 0·3 at 232·6, 272·6 and 301·3 K with ΔH_f⁰H_f = ?6·6 ± 1·4 kJ mol^?1 for the VC -(SO₂)₂ complex. The chemical shift of the trans β-proton was twice that of the other two protons. indicating that SO₂ adopts an asymmetric orientation to the double bond.     

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].     

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     

Radiation-induced copolymerization of isobutyl vinyl ether with trichloroethylene

The radiation-induced copolymerization of isobutyl vinyl ether with trichloroethylene was investigated in the temperature range from ?50°C to 100°C over a wide range of comonomer compositions. A copolymer was obtained in which the monomers alternate with regularity along the polymer chain over essentially the entire range of comonomer compositions. Both the rate of copolymerization and the number-average molecular weight of the resulting copolymer were found to depend strongly on the initial comonomer composition. The monomer reactivity ratios were determined and correspond well with calculated values. An apparent activation energy of 3.2 kcal/mole was obtained for the copolymerization process which exhibits a dose rate dependence of 0.72. The number-average molecular weight was found to be strongly dependent on the irradiation temperature, reaching a maximum value at 5°C.     

Radiation-induced copolymerization of ethylene and sulfur dioxide in the liquid and gas phases

The radiation-induced copolymerization of ethylene and sulfur dioxide has been studied in the liquid and gas phases. In the liquid phase, the copolymer composition remained equimolar over a temperature range of 20–160°C. and ethylene pressures of 50–680 atm. The rate of copolymerization in the liquid phase at 680 atm. increased with temperature to a maximum value at ～80°C. Above this temperature the rate steadily decreased to zero at 157°C. because of temperature-dependent depropagation reactions. In the gas phase, copolymers were formed that contained from 9 to 46 mole-% sulfur dioxide. Under constant conditions of temperature, pressure, and radiation intensity, the copolymerization rate in the gas phase increased with increasing sulfur dioxide in the initial gas mixture. The propagating species for the liquid-phase experiments is considered to consist of an equimolar complex molecule of ethylene and sulfur dioxide. For gas mixtures containing an excess molar concentration of ethylene, the propagating species are ethylene and the complex molecule. Infrared spectra show polysulfone structures. Calorimetric and x-ray diffraction analyses indicate crystalline structures for copolymers in the range 9–50 mole-% sulfur dioxide, although a melt transition temperature could not be observed for copolymer containing >31 mole-% sulfur dioxide. Clear uniform film was obtained with copolymers containing up to 31 mole-% SO₂.     

Copolymerization of ethylene and 1-butene using a Cr—silica catalyst in a slurry reactor

A novel slurry reactor was used to investigate the copolymerization behavior of ethylene and 1-butene in the presence of 1 wt % Cr on Davison silica (Phillips-type) catalyst over the temperature range of 0–50°C, space velocity of about 0.0051 [m³ (STP)]/(g of catalyst) h, and a fixed ethylene to 1-butene feed mole ratio of 95 : 5. The effect of varying the ethylene to 1-butene feed ratios, 100 : 0, 96.5 : 3.5, 95 : 5, 93 : 7, 90 : 10, 80 : 20, and 0 : 100 mol/mol at 50°C was also studied. The addition of 1-butene to ethylene typically increased both copolymerization rates and yields relative to ethylene homopolymerization with the same catalyst, reaching a maximum yield for an ethylene: 1-butene feed ratio of 95 : 5 at 50°C. The incorporation of 1-butene within the copolymer in all cases was less than 5 mol %. The average activation energy for the apparent reaction rate constant, k_a, based on total comonomer mole fraction in the slurry liquid for the ethylene to 1-butene feed mole ratio of 95 : 5 in the temperature range of 50–30°C measured 54.2 kJ/mol. The behavior for temperatures between 30 to 0°C differed with an activation energy of 98.2 kJ/mol; thus, some diffusion limitation likely influences the copolymerization rates at temperatures above 30°C. A kinetics analysis of the experimental data at 50°C for different ethylene to 1-butene feed ratios gave the values of the reactivity ratios, r₁ = 27.3 ± 3.6 and r₂ ≅ 0, for ethylene and 1-butene, respectively. © 1996 John Wiley & Sons, Inc.     

氯乙烯/N-苯基马来酰亚胺悬浮共聚合速率的研究

考察了单体配比、温度、引发剂浓度诸因素对氯乙烯（ＶＣ）／Ｎ－苯基马来酰亚胺（ＰＭＩ）悬浮共聚速率的影响．ＶＣ／ＰＭＩ共聚有显著的交叉终止,致使共聚速率降低,测得交叉终止速率常数的函数＝５．７７,ＰＭＩ均聚综合速率常数的倒数值δ２＝５３．６５,共聚表观活化能Ｅａ＝１２７．９ｋＪ／ｍｏｌ,增长活化能Ｅｐ＝６３．７ｋＪ／ｍｏｌ,聚合速率对引发剂浓度的反应级数为０．７８６．并对ＶＣ／Ｎ－环己基马来酰亚胺（ＣＨＭＩ）和ＶＣ／ＰＭＩ两个体系进行了比较     

Quasiliving Carbocationic Polymerization. XV. Forced Ideal Copolymerization of Isobutylene-lsoprene

Forced ideal carbocationic copolymerization of isobutylene and isoprene has been achieved by continuous addition of monomer mixtures of different compositions to cumyl chloride/TiCl₄ charges at -50°C. The overall rate of copolymerization could be kept equal to that of addition rate with up to 10 mol% isoprene in the mixed monomer feed. In this monomer concentration range the composition of the copolymer was identical to that of the feeds. At higher diene concentrations in the feed, chain transfer to monomer and other side reactions (intramolecular cyclization, gel formation) could not be completely avoided. The number-average molecular weight of the copolymers increased almost linearly with the amount of consumed monomers at 10 mol% isoprene concentrations in the feed (i.e., in the quasiliving range). According to ¹H-NMR and ¹³C-NMR spectroscopy, the products are random copolymers.     

Quasiliving Carbocationic Polymerization. IX. Forced Ideal Copolymerization of Styrene Derivatives

Forced ideal carbocationic copolymerization of α-methylstyrene (αMeSt) with p-tert-butylstyrene (ptBuSt) and (αMeSt) with styrene (St) has been achieved by continuous monomer feed addition to a cumyl chloride/BCl₃ charge at -50°C by keeping the feeding rate of the monomer mixtures equal to the overall rate of copolymerization, The composition of the copolymers was identical to the composition of the monomer feeds over the entire concentration range. A quantitative expression has been derived to show that under forced ideal copolymerization conditions the composition of the copolymer can be controlled by the composition of the feed. Further, conditions have been found for forced ideal quasiliving copolymerizations, i.e., the number-average molecular weight of the copolymers increased almost linearly with the cumulative weight of consumed monomers by the use of suitably slow, continuous feed addition in the presence of relatively nonpolar solvent mixtures (60/40 v/v n-hexane + methylene chloride). In polar solvent (methylene chloride) the molecular weight increase was less pronounced due to chain transfer to monomer involving indane-skeleton formation; however, with charges containing large amounts of ptBuSt the molecular weight increase was surprisingly strong. Interestingly, ptBuSt does not homopolymerize in 60/40 v/v n-hexane/methylene chloride but it readily copolymerizes with αMeSt. This observation was explained by examining the relative rates of terminations of the cationic species involved. Conditions have been found for the pronounced quasiliving polymerization of St. In forced ideal quasiliving copolymerizations neither the molecular weights of αMeSt/ptBuSt or αMeSt/St copolymers nor the initiating efficiencies of the initiating systems used show a depression. The microstructure of representative αMeSt/ptBuSt copolymers obtained under forced ideal quasiliving conditions has been analyzed by ¹³C-NMR spectroscopy. According to these studies, true copolymers have formed and resonance peaks for various triads have been deduced.     

Donor-Acceptor Complexes in Copolymerization. XXXVI. Alternating Diene-Dienophile Copolymers. 4. Copolymerization of Furan and 2-Methylfuran with Maleic Anhydride

Abstract

The copolymerization of furan and 2-methylfuran with maleic anhydride in the presence of a radical catalyst yields equimolar, alternating copolymers in which the furan units have a 2,5-linkage (NMR and IR). The copolymerization appears to have a floor temperature of about 40°C. The furan-maleic anhydride Diels-Alder adduct polymerizes in solution in the presence of a radical catalyst at temperatures above 60°C to yield the identical copolymer as is obtained from the monomers. The adduct undergoes a retrograde reaction above 60°C to regenerate the monomers which then copolymerize through excitation of the ground state comonomer charge transfer complex.     

Gamma Ray Induced Low Temperature in Situ Polymerization of Vinyl Chloride and Copolymfrization of Vinyl Chloride-Vinyl Acetate in Taiwan-Produced Woods

Gamma radiation induced polymerization of vinyl chloride (VC) and copolymerization of vinyl chloride (VC)-vinyl acetate (VAc) in Taiwan cedars have been investigated at low temperatures. The polymerization-rate of VC and the copolymerization-rate of VC-VAc system in wood were found to be proportional to the n powers of the dose-rate, where n became close to the value of 1 as the polymerization temperature being lowered below 0°C. The oxygen in air was recognized to induce the delay of the induction period due to its retardation on the polymerization. The apparent activation energies of VC and VC-VAc for the polymerization and the copolymerization in wood were determined by use of the Arrhenius plotting as 4.0 Kcal/mole and 3.4 Kcal/mole respectively at the temperature-range of —15°C～20°C. The degree of polymerization of VC was greatly affected by the polymerization temperature, although it was observed to be independent on the total gamma dose within 1 Mrad and the kinds of wood. No graft reaction of PVC polymer and PVC-PVAc copolymer onto the wood cellulose was found, while low graft percentage of about 3% being obtained at 20° C in the case of using swelling agents. However, this value was found to be decreased to 0.1% at the temperature of —15°C. Based on the above-mentioned experimental results, the radiation induced low temperature polymerization of VC or copolymerization of VC-VAc system in Taiwan produced cedars are considered to proceed with radical polymerization mechanism.     

Copolymerization of allyl esters of some fatty acids

Attempts have been made unsuccessfully to homopolymerize a number of allyl esters of substituted fatty acids by radical initiation in emulsion systems. Copolymerizations of these allyl esters with styrene, methyl methacrylate, and vinyl chloride have been investigated. Of these comonomers, styrene and methyl methacrylate do not copolymerize well with the allyl esters, whereas vinyl chloride does. Reactivity ratios for the radical copolymerization of allyl 11-iodoundecanoate, M₁, and vinyl chloride, M₂, determined at 60°C. in benzene, are r₁ = 0.42 and r₂ = 1.64. A copolymer of allyl 10, 11-dibromoundecanoate and vinyl chloride was fractionated and found to be fairly homogeneous.     

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.     

On the thermal degradation of poly(styrene sulfone)s: II. Determination of copolymer triad sequence composition

The composition of the poly(styrene sulfone)s formed were measured for comonomer liquid mixtures with Xst=0.10.9 at the temperature of 50°C. Copolymerization was initiated with AIBN as the initiator. The copolymer composition showed an increase with an increasing amount of comonomer. The copolymerization of styrene with sulfur dioxide to form a variable composition polysulfone with an average styrene:sulfur dioxide molar ratio n≥1.0 was also examined. The pen-penultimate modeling of copolymerization was used to account for the triad monomer sequence and composition of poly(styrene sulfone). It was found that the theoretical modeling of copolymerization can very effectively evaluate the triad monomer sequence and composition of poly(styrene sulfone).     

Copolymerization of styrene with vinyltriethoxysilane and vinyltriacetoxysilane

Styrene was copolymerized in bulk with vinyltriethoxysilane at 80°C and vinyltriacetoxysilane at 60, 80, and 100°C with the use of benzoyl peroxide as an initiator at low conversions. Copolymer composition was determined from the silicon content and reactivity ratios were calculated by the conventional scheme of copolymerization. The low r₁ value (styrene) in the styrene-vinyltriacetoxysilane system (St–VTAS) as compared to styrene-vinyltriethoxysilane (St–VTES) copolymerization may be attributed to higher reactivity of VTAS towards the polystyryl radical. Further, in the St–VTAS system, r₁ tends to decrease with increasing polymerization temperature. The influence of silicon comonomer on properties of the copolymers (intrinsic viscosity, solubility, dielectric and thermal behavior) was studied.     

The Spontaneous Copolymerization of Indene with Polar Vinyl Monomers in the Presence of Zinc Chloride

Indene (ID) was found to copolymerize spontaneously with polar vinyl monomers containing a nitrile or ester group in the presence of ZnCb and to give rise simultaneously to its cationic homopolymer in the latter comonomer. The formation of a 1:1-charge transfer complex between ID with acrylonitrile coordi-nated to ZnCl₂ ((AN)c) was confirmed by UV-spectroscopic studies and the equilibrium constant for it was estimated to be 0.121 L/mol in AN at 25°C. The overall activation energy for the copolymerization with (AN)c was obtained to be ～9.8 kcal/mol. An increasing amount of ZnCl₂ in AN resulted in increases in the copolymerization rate, viscosity, and alternating tendency of the copolymer. The addition of 1, 1-diphenyl-2-picrylhydrazyl to the System ID-(AN)c retarded the copolymerization and induced a cationic polymerization of ID. Further, terpolymers containing ～50 mol % AN were formed spontaneously in the System ID-styrene-(AN)c. Comparing these results with the corresponding ones obtained for 1,3-cyclodienes as donor monomer reported previously, a discussion is given on the reactivity of ID-(AN)c complex in the initiation and the propagation of the copolymerization. The mechanism of the attendant cationic polymerization of ID is briefly considered.