Polymerization of alkyl allyl oxalates in the evolution of carbon dioxide at elevated temperatures

Radical polymerization of several alkyl allyl oxalates, including methyl allyl oxalate (MAO), ethyl allyl oxalate, propyl allyl oxalate, butyl allyl oxalate, and octyl allyl oxalate, was conducted in the evolution of carbon dioxide at elevated temperatures, and was compared with the anomalous polymerization behavior of diallyl oxalate (DAO) discussed in our earlier article

1 A. Matsumoto, I. Tamura, M. Yamawaki, and M. Oiwa, J. Polym. Sci. Polym. Chem. Ed., 17 , 1419 (1979).

. The kinetic equations for the polymerization of alkyl allyl oxalate were derived following the kinetic treatment of the DAO polymerization by further consideration of the absence of cyclization of the growing polymer radical and the effective reinitiation by alkyl radical, and were then satisfactorily applied to the polymerization of MAO, as a representative alkyl allyl oxalate. The evolution of carbon dioxide in the polymerization of alkyl allyl oxalates was enhanced with the increase of bulkiness of the alkyl substituent, as a result of steric suppression of the propagation of the growing polymer radical.     

Studies of the Polymerization of Diallyl Compounds. XL. Correlation between Addition Modes and Evolution of Carbon Dioxide in the Polymerization of Diailyl Oxalate

The occurrence of head-to-head (HH) addition in the radical polymerization of diallyl oxalate (DAO) was examined under various polymerization conditions. The content of HH linkage in poly (DAO) was reduced in comparison with allyl acetate and diallyl succinate; this may be ascribed to the high polarity of DAO inducing a polar effect on the intermolecular propagation of the growing polymer radical, resulting in reduced HH addition. The correlation between addition modes and evolution of carbon dioxide characteristic of DAO polymerization at elevated temperatures is mechanistically discussed in detail, with special focus on the solvent effect and the reduced dismutation of the cyclized radical compared to the uncyclized one.     

Studies of the polymerization of diallyl compounds. VII. Kinetics of the polymerization of diallyl esters of aliphatic dicarboxylic acids

Radical polymerization studies on diallyl oxalate (DAO), diallyl malonate (DAM), diallyl succinate (DASu), diallyl adipate (DAA), and diallyl sebacate (DAS) have been conducted kinetically from the standpoint of cyclopolymerization. Benzoyl peroxide was employed as the initiator. The initial overall rate of polymerization, R_p was not proportional to the square root or the first power of the initiator concentration, [I]. But R_p/[I]^1/2 and [I]^1/2 bore a linear relationship, provided the monomer concentration was kept constant. The residual unsaturation of the polymers decreased with decreasing monomer concentration. The ratio of the rate constant of the unimolecular cyclization reaction to that of the bimolecular propagation reaction of the uncyclized radical, K_c, was evaluated from the above relationship between the residual unsaturation and the monomer concentration at 60°C. The K_c values obtained were 3.6, 3.2, 2.8, 2.5, and 1.2 mole/l. for DAO, DAM, DASu, DAA, and DAS, respectively. The overall activation energies of polymerization were found to be 21.1 (DAO), 24.2 (DAM), 21.7 (DASu), 22.0 (DAA), and 22.2 (DAS) kcal/mole.     

Studies of the polymerization of diallyl compounds. XXIV. Effect of temperature on the polymerization of diallyl phthalate

The effect of temperature on the polymerization of diallyl phthalate was investigated in the temperature range of 80–150°C. The degree of polymerization increased slightly with temperature up to 100°C and then decreased; together with the results of primary chain length and the dependence of R_p on initiator concentration, these findings were interpreted in terms of the enhancement of the reinitiation ability of the allylic radical produced by the intramolecular chain-transfer reaction and of the reactivity of the cyclized radical at elevated temperature. The tendency for cyclization became more marked with increasing temperature. The gel point was almost unaffected.     

Studies of the polymerization of diallyl compounds. XXVI. Enhanced polymerizability by the hydroxyl group in the polymerization of diallyl hydroxydicarboxylates

In order to elucidate the effect of the hydroxyl group on the polymerization of diallyl hydroxydicarboxylates, we investigated in detail the radical polymerizations of diallyl succinate (DASu), diallyl malate (DAMa), and diallyl tartrate (DATa), each of which have similar structure differing only in the number of hydroxyl groups present. The rate of polymerization (R_p) was quite enhanced in the order DASu < DAMa < DATa, in accord with the increase in the number of hydroxyl groups within a monomer unit. The enhanced ability of the allylic monomer radical to reinitiate chain growth was also in the same order, as was clear from the dependence of R_p on the initiator concentration. The dependence of the residual unsaturation of the polymer on the monomer concentration in the polymerizations of DAMa and DATa was abnormal in terms of cyclopolymerization. These results are discussed in connection with the formation of the intermolecular hydrogen bond through the hydroxyl groups.     

Studies of the polymerization of diallyl compounds. XI. Polymerization of styrene in the presence of diallyl compounds

Radical polymerization of styrene in the presence of various diallyl compounds was carried out at 60°C, with the use of 2,2′-azobisisobutyronitrile as an initiator. The chain transfer constant C_s of the styryl radical to diallyl compounds was determined graphically by solving the Mayo equation. The C_s values of diallyl esters are quite small compared to those of diallyl acetals. The polymerization mechanism of styrene in the presence of diallyl compounds was also discussed in connection with the results obtained previously.     

Studies of the polymerization of diallyl compounds. XLI. Discussion of substantially identical gel points among three isomeric diallyl phthalates

In the bulk polymerization of three isomeric diallyl phthalates, diallyl phthalate (DAP), diallyl isophthalate, and diallyl terephthalate (DAT), no difference in the actual gel point was substantially observed. This interesting gelation behavior is discussed in terms of the correlation between gelation and the difference in cyclization modes, and the difference in reactivity between the uncyclized and cyclized radicals for crosslinking; the nonconsecutive addition in DAT polymerization led to a delayed gelation and the cyclized radical in DAP polymerization showed an enhanced reactivity for crosslinking.     

Polymerization of diallyl phthalate and gelation of poly(diallyl phthalate) by copolymerization with styrene

In the polymerization of diallyl phthalate in bulk at 60°C with azobisisobutyronitrile, extensive branching of the polymers obtained before gelation was ascertained from the enhanced broadening of the molecular weight distribution, coupled with the decrease of the residual unsaturation. Copolymerization of poly(diallyl phthalate) and styrene in bulk at 80°C with benzoyl peroxide was studied in detail with regard to the gel formation. The gel time increased with increasing fraction of styrene in feed. Both the gel yield and the conversion of styrene incorporated into the gel increased steadily with polymerization time, even after the total conversion of styrene exceeded 95%. The polystyrene recovered by saponification of the gel was found to carry hydroxyl groups, which should come from the copolymerized diallyl phthalate units. It was concluded that styrene behaved as a diluent in the early stage, and that the crosslinking after gelation of the system proceeded mainly through polymer–polymer reactions involving the occluded polystyryl radicals and poly(diallyl phthalate).     

Studies of the polymerization of diallyl compounds. XXV. Gel point in the polymerization of diallyl esters of aromatic dicarboxylic acids

Studies on gelation in the radical polymerization of diallyl dicarboxylates have been conducted by Simpson,^9,11 Gordon,¹⁰ and Oiwa.¹³ However, the results obtained have not always been consistent and are still far from full elucidations. In this paper, the gel point in the polymerization of diallyl aromatic dicarboxylates, including diallyl phthalate (DAP), diallyl isophthalate (DAI), and diallyl terephthalate (DAT) is experimentally reexamined in detail and discussed according to Gordon's theory; the discrepancy between actual and theoretical gel point conversion was quite large and was enhanced in the order DAT > DAI > DAP. Moreover, from detailed inquiry into the primary chain length of the prepolymer it is suggested that the intramolecular chain transfer reaction plays an important role in the polymerization of diallyl ester accompanying the intramolecular cyclization reaction. The polydispersity coefficient (P _w,0/P _n,0) of the initial prepolymer of DAP is also estimated to be 2.0 from the extrapolation of P _w/P _n to zero conversion.     

Ternary copolymerization involving diallyl compounds and sulfur dioxide

Ternary radical copolymerization of diallyl and vinyl monomers with sulfur dioxide was studied. High activity of sulfur dioxide in formation of donor-acceptor complexes with unsaturated compounds allows diallyl compounds, which are weakly active under the conditions of radical initiation, to be involved in copolymerization with vinyl monomers to give ternary copolymers containing various functional groups.     

Cyclocopolymerization of diallyl ether with sulfur dioxide in acetone

The radical polymerization of diallyl ether (DAE) with sulfur dioxide produced soluble copolymers whose composition was between 1:1 and 2:1 in SO₂. The overall rate was maximum at a 2:1 feed composition in SO₂. A cyclocopolymerization scheme, which was based on cross propagations and the intramolecular cyclization of DAE radical, was applied. The energy of activation was larger for the uncyclized DAE radical in undergoing the cross propagation with SO₂ than in undergoing the intramolecular cyclization with the pendent allylic group by 40 kJ/mol. Formation of rings made of DAE and SO₂ and 3,4-disubstituted-tetrahydrofuran rings by the cyclized DAE units on the main chain was proposed on the basis of the ¹H-NMR spectra.     

Studies of the polymerization of diallyl compounds. XXVIII. Copolymerization of monoallyl phthalate with allyl benzoate and diallyl phthalate

The bulk copolymerizations of monoallyl phthalate (MAP) with allyl benzoate (ABz) and diallyl phthalate (DAP) were conducted in the presence of benzoyl peroxide as an initiator at 70°C; copolymers containing allyl alcohol unit were obtained. The copolymer composition was reasonably interpreted in terms of polymerization kinetics, including the partial elimination of phthalic anhydride (PhA) from the MAP growing chain end in its propagation reaction with another monomer. Kinetics of the copolymerization of DAP with MAP were also discussed in detail, and the gel point was additionally evaluated. DAP–MAP copolymer was homogeneously reacted with zinc acetate to produce the polymer gel carrying ionic crosslinkages.     

Liquid carbon dioxide as a solvent for the radiation polymerization of ethylene

The usefulness of liquid carbon dioxide as a solvent for polymerization of ethylene was studied. The effect of liquid carbon dioxide on the polymerization was investigated under conditions of the pressure of 400 kg./cm.² over the temperature range 20–45°C. by using γ-radiation and AIBN as initiators. The infrared spectrum of the polymers showed that carbon dioxide had little effect on the polymer structure. The polymers contained no combined carbon dioxide and only small amounts of vinylidene unsaturation. The methyl content of the polymers was 0.5–4.0 CH₃/1000C. The polymer yield and molecular weight were found to be decreased by the addition of carbon dioxide in both polymerization by γ-radiation and AIBN. The number of polymer molecules formed per unit time increased with the content of carbon dioxide in the γ-ray polymerization, and was constant in the case of AIBN. The advantages of the use of liquid carbon dioxide as a solvent in this polymerization were also considered from the viewpoints of the continuous process, the separation of polymer, the stability of carbon dioxide to radiation, and commercial applications.     

Polymerization of oriented monomers. IX. Further studies on the polymerization and vesicular properties of allyl and diallyl based monomeric and polymerized quaternary ammonium salts

The polymerization of the previously reported allyl and diallyl quaternary ammonium salts, which from vesicles in water, to their polymerized analogs was further investigated. The structure of the polymer derived from the diallyl derivative, for which some controversy existed, was elucidated by ¹³C-NMR spectroscopy. Mixed vesicles, based on the monoallyl monomer and incorporating certain vesicle forming quaternary ammonium salts, cholesterol, or cholesteryl acrylate were also formed. These mixed vesicles were characterized primarily as far as their stability is concerned. It was found that the incorporation of the additives does not enhance the stability of the mixed vesicles compared to that exhibited by monoallyl simple vesicles. In addition, polymerization of mixed monoallyl-cholesteryl acrylate vesicles results in the destruction of their structure. On the contrary, simple polymerized vesicles, resulting from the diallyl monomer, showed excellent long-term stability. Specifically, samples prepared two years ago are still dispersed and, very possibly, they will remain so for a longer period since they are not showing signs of precipitation.     

Mobility of the ring structure and the characteristics of crosslinked polymers: The structural effect of the eleven-membered ring and its homologs upon the dynamic mechanical properties and glass transition temperature of crosslinked diallyl succinate polymers

Dynamic mechanical properties and glass transition temperatures were measured for crosslinked polymers derived from diallyl succinate monomers. The mobility of the diester having an eleven-membered ring and of homologous structures which are introduced in the crosslinked polymer system, is discussed on the basis of the parameter for cyclization polymerization of a monomer, dynamic mechanical properties, and glass transition temperature. Control of the mobility of the ring structure and its homologous structures involved in the crosslinked polymers was attempted by modification of the substituent at the 1- or 1,2-position of diallyl succinate, and the diallyl succinate monomers were derived from the succinic acid and its derivatives: succinic acid, methyl succinic, ethyl succinic, and chlorosuccinic acids; cis-1,2-dicarboxylic acids of cyclopropane, cyclobutane, cyclopentane, and cyclohexane; cis-1,3- and 1,4-dicarboxylic acids of cyclohexane, and phthalic acid. The results obtained are explained well on the basis of the mobility of the ring and homologous structures.     

Polymerization initiated by an electron donor–acceptor complex. Part IV. Kinetic study of polymerization of methyl methacrylate initiated by the charge-transfer complex consisting of poly-2-vinylpyridine and liquid sulfur dioxide

A kinetic study has been made of the polymerization of methyl methacrylate (MMA) initiated by a charge-transfer complex of poly-2-vinylpyridine (electron donor) and liquid sulfur dioxide (acceptor) in the presence of carbon tetrachloride. It is concluded that the polymerization proceeds through free-radical intermediates, as with the pyridine-liquid sulfur dioxide complex system. The association constants K of acceptor and polymer electron donors which range widely in their molecular weight were determined spectrophotometrically, and it has been found that both K and overall rate of polymerization R_p of MMA decrease with increasing molecular weight of polymer donor; contrary to this, molecular weight of PMMA formed increases with increasing molecular weight of the polymer donor. Other kinetic behaviors was essentially the same as in the pyridine–liquid sulfur dioxide system, i.e., R_p is proportional to the square root of the concentration of the complex and to the 3/2-order of the monomer concentration; R_p is clearly sensitive to the carbon tetrachloride concentration at low concentration of carbon tetrachloride, but for a higher concentration it is practically independent of the carbon tetrachloride concentration. It has been deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–polymer donor and the monomer.     

Cationic polymerization of formaldehyde in liquid carbon dioxide. Part I

A cationic polymerization of formaldehyde which gave a high molecular weight polymer was studied in liquid carbon dioxide at 20–50°C. In the polymerization without any catalyst both the rate of polymerization and the molecular weight of the resulting polymer increased rapidly with a decrease in the loading density of the monomer solution to the reaction vessel, and also increased with an increase in the initial monomer concentration. From these results it was concluded that the initiating species could be ascribed to an impurity contained in the monomer solution. Both the rate of polymerization and the degree of polymerization of the polymer also increased with rising temperature. The carboxylic acid added acted as a catalyst in the polymerization because of increase in the polymer yield, the molecular weight of polymer formed, and the number of moles of polymer chain with increasing dissociation constant of acid used. It was concluded that the polymerization in liquid carbon dioxide proceeded by a cationic mechanism. Methyl formate had no influence on the polymerization, but methanol and water acted as a chain-transfer agent.     

Continuous precipitation polymerization of acrylic acid in supercritical carbon dioxide: The polymerization rate and the polymer molecular weight

The precipitation polymerization of acrylic acid in supercritical carbon dioxide was studied in a continuous stirred tank reactor with 2,2′‐azobis(2,4‐dimethylvaleronitrile) as the free‐radical initiator. The reactor temperature was between 50 and 90 °C, the pressure was 207 bar, and the average residence time was between 12 and 40 min. The product polymer was a white, dry, fine powder that dissolved in water. A wide range of polymer molecular weights (5–200 kg/mol) was obtained. The effects of the operating variables on the polymerization rate and on the polymer molecular weight were evaluated. The observed kinetics suggested that polymerization took place in both the supercritical fluid and the precipitated polymer particles. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2546–2555, 2005     

Bulk polymerization of diallyl benzene-dicarboxylates I. Influence of temperature on allyl group reactivity

The bulk polymerization of the three isomeric diallyl benzene-dicarboxylates was carried out in the temperature range 80–285°C. The progress of the polymerization process was examined by determination of the conversion of allyl groups double bonds. The reactivity of these groups in the polymerization increases in the following order of isomers: ortho < para < meta at 80–230°C. At temperatures above 200°C the thermal polymerization with activation energies for ortho, meta and para isomers 32, 27, and 28 kcal/mol of allyl group, respectively, has been observed. With the increase of temperature from 80 to 230°C for each of the monomers the number of allyl groups consumed when forming one C? C chain (degree of chain polymerization) decreases, but at the same time the kinetic chain length increases several times. The results have been explained by the growing role of chain transfer reactions with simultaneous increase of an ability to reinitiation by occured radicals. The mechanisms of thermal polymerization have been proposed.     

Polymerization of allyl esters of unsaturated acids. IV. Cyclopolymerization of diallyl maleate

Radical polymerization of diallyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′-azobisisobutyronitrile as an initiator and benzene as a solvent at 60°C. Thus, the kinetic equations involving bicyclo-intramolecular cyclization are derived by assuming steady-state conditions for the different types of radicals, and various parameters involved in the equations are then estimated approximately from an extension of the corresponding model experimental results. The validity of these treatments is confirmed from the comparison with the experimental data including the relationships between the contents of the unreacted allylic and maleic double bonds and the monomer concentrations. In addition, the sequence distribution of the structural units of the polymer produced is discussed; for example, the content of the bicyclic structural units is estimated to be 47.2% at a 10% dilution of the pure monomer.