Kinetics of the polymerization of potassium p-styrenesulphonate in various media

The free radical polymerization of potassium p-styrenesulphonate has been investigated at 70° for solutions in dimethyl sulphoxide (DMSO)-water mixtures (1:3 and 3:1) and in DMSO using 2,2′-azobisisobutyronitrile as initiator. The kinetic orders with respect to monomer and initiator increase but the rate of polymerization, the value of $\text{k}{}_{\mathrm{p}}\text{/k}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}_{\mathrm{t}}$ and the average molecular weight of the resulting polymer decrease with increasing DMSO concentration in the DMSO-water mixture. These effects have been attributed to changing of parameters of the electrostatic interactions in the system “macroradical-counterions-anions of monomer” with change of composition of the medium.     

Effects of reaction medium on the radical polymerization and copolymerization of acrylamide

Papers on the free radical polymerization and copolymerization of acrylamide have been examined. It has been shown that change in the nature of the solvent (polarity, dielectric constant etc.). pH, addition of complexing agents and surfactants, temperature, the nature of initiator, concentration of monomer and other factors may influence not only the rate of polymerization but also the properties of the resulting polymers, particularly the degree of polymerization. The parameters influencing the copolymerization of acrylamide with vinyl monomers have also been analysed. It is shown that the classical Mayo-Lewis equation and the Alfrey and Price Q-e scheme may not be applicable to systems where one of the monomers is acrylamide.     

Effect of reaction medium on ionic lactam polymerization

Ring-size and substitution greatly affect the permittivity and donor-acceptor properties of lactams and their derivatives as well as of the corresponding polymers. Permittivity changes occurring during bulk polymerization affect dissociation equilibria and the very high increase in permittivity during polymerization is responsible for the autoacceleration observed in the anionic polymerization of the seven-membered lactam. In diluted solution, pronounced effects of the nature of solvent or additive have been observed in anionic polymerization of substituted four-membered lactams. Whereas the initial rate of polymerization is independent of the monomer concentration, the apparent order in the monomer increases and the rate of polymerization in most solvents decreases during polymerization, except in solvents of very low polarity. Changes of permittivity and conductivity during and after polymerization indicate, that changes in the solvation and rearrangement of the growth center are responsible for its varying activity. These processes increase the reactivity during ageing of the living system. Similarly to other heterocyclic monomers, the cationic polymerization of N-acyllactams is rather insensitive to the permittivity of the reaction medium.     

Effect of reaction medium on copolymerization of acrylonitrile and methyl acrylate

The copolymerization of acrylonitrile (AN) with methyl acrylate (MEA) has been investigated in three types of polymerization, i.e., emulsion polymerization in water with a water-soluble initiator, suspension polymerization in water with an oil-soluble and water-insoluble initiator, and solution polymerization in dimethyl sulfoxide (DMSO). Monomer reactivity ratios at 50°C. for AN and MEA are found to be r₁ = 0.78 ± 0.02, r₂ = 1.04 ± 0.02 in emulsion polymerization; r₁ = 1.02 ± 0.02, r₂ = 0.70 ± 0.02 in DMSO solution polymerization; r₁ = 0.75 ± 0.05, r₂ = 1.54 ± 0.05 in suspension polymerization. The large differences found in the reactivity ratios may be attributed to the different ratio of concentration of two monomers in the loci of polymerization. Chemically, AN is somewhat more reactive than MEA as shown by the reactivity ratios in DMSO. In the case of the suspension polymerization, the MEA/AN ratio in the polymer particles in which polymerization occurs may be higher than that in the total phase. Experimental results of the emulsion polymerization show that the emulsion polymerization of AN occurs both in the particles and in water. In addition, rates of the copolymerization of AN with MEA have also been investigated.     

Radical copolymerization of acrylic monomers. IV. Effect of substituents on the radical polymerization and copolymerization of phenyl acrylates

The kinetics of radical polymerization of phenyl, ortho-chlorophenyl, and para-chlorophenyl acrylates, as well as their copolymerization with methyl methacrylate, have been studied dilatometrically. The results obtained indicate that the overall rate of polymerization is affected by the flexibility of the growing radicals. However, the copolymerization of these monomers with methyl methacrylate gives overall rates rather similar for all three systems, being fundamentally regulated by the formation of reversible π complexes between the donor aromatic rings and the acceptor methacrylic double bonds. Dilatometric methods for the study of the copolymerization reactions have been tested and the corresponding binary bonding frequencies B_ij and conversion factors K_ij have been calculated for the copolymerization of ortho- and para-chlorophenyl acrylates with methyl methacrylate.     

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.     

Effect of substituent position and lithium,sodium and potassium on the electronic structure of o-, m- and p-methoxybenzoic acids

We have studied the effect of the substituent position in the ring, and lithium, sodium and potassium ions on the electronic structure of o-, m- and p-methoxybenzoic acids (anisic acids) by the use of FT-IR, FT-Raman, Ar matrix FT-IR and ¹H NMR methods, and ab initio calculations at the B3LYP/6-311++G** level of theory. Characteristic shifts of the bands in the spectra and changes in the band intensities along the metal and ligand series were observed. On the basis of the obtained results we may answer the questions: (1) do the substituents in the benzene ring influence the electronic charge distribution in the carboxylic group of anisic acids and alkali metal anisates, (2) do the metal ions affect the electronic charge distribution in the methoxy group, (3) in what way do the alkali metals affect the electronic system of o-, m- and p-anisic acids? The substitution of lithium, sodium and potassium ions in the carboxylic group of o-, m- and p-anisic acids causes changes in the values of bond lengths and angles, and in the electronic charge distribution in the carboxylic group, methoxy group and aromatic ring. The influence of alkali metals on the electronic structure of the ligands is weaker than the effect of methoxy substituents. The effect of Li, Na and K ions on the aromatic ring of the ligands is mostly noticeable in the case of the ortho isomer. The carboxylic and methoxy groups situated in ortho positions in the ring weaken the effect of the alkali metals on the electronic charge distribution in the carboxylic anion and methoxy group.     

Effect of solvent on chain propagation and termination reaction rates in radical polymerization

The radical polymerizations of acrylamide and methacrylamide and of acrylic, methacrylic and fluoroacrylic acids have been studied in various solvents. The nature of the solvent affects the overall rate due to changes in k_p and E_p. It has been shown that the effect of solvent also depends on the nature of the monomer. A possible explanation of the observed behaviour is discussed.     

An enzyme-assisted polymerization. Effect of the reaction medium for the controlled polymerization of fluoroamino acids

Chiral fluoroamino acids were polymerized with cellulase and/or modified cellulase. A number of chiral fluorinated polyamides of narrow molecular weight distribution were prepared. The degree of polymerization is controlled by the matching of enzyme-form and reaction medium.     

Novel ionic liquids as reaction medium for atom transfer radical polymerization of methyl methacrylate

Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) employing ethyl 2-bromoisobutyrate (EBiB)/ CuBr as the initiating system was investigated at 50℃ in the absence of any additional ligand in the three room temperature ionic liquids (RTIL_s), 1-methyl-imidazolium acetate ([mim][CH_3COO]), 1-methylimidazolium propionate ([mim][CH_3CH_2COO]) and 1-methylimidazolium butyrate ([mim][CH_3CH_2CH_2COO]), respectively. All the polymerization in the three RTILs proceeded in a well-controlled manner. The sequence of the apparent polymerization rate constants was kapp([mim][CH_3COO]) > kapp([mim] [CH_3CH_2COO]) > kapp ([mim][CH_3CH_2CH_2COO]).     

Atom transfer radical polymerization and copolymerization of isoprene catalyzed by copper bromide/2,2'-bipyridine

ATRP, as one of the most successful controlled/‘‘living' radical polymerization techniques, has been applied to a large variety of monomers including styrenes,(meth)acrylates,(meth)acrylamides,acrylonitrile, and vinyl acetate. However, ATRP of isoprene still remains a challenge due to poor solubility of copper catalysts in isoprene and low chain propagation rate constant of the monomer. In this work,Cu Br/2,2'-bipyridine was found to effectively mediate ATRP of isoprene at 100 °C, 130 °C, and 150 °C with ethyl 2-bromopropionate as an initiator. The polymerizations proceeded smoothly and reached 48.1%,53.3%, and 71.0% conversions, respectively, in 72 h, producing polyisoprenes with molecular weights close to theoretical values and relatively narrow distributions. A block copolymer of polystyrene-bpolyisoprene was prepared using Cu Br/2,2'-bipyridine as a catalyst and polystyrene as a macroinitiator.The ~1H NMR and ~(13)C NMR analysis of polyisoprene indicated that the polymer had 88.8% 1,4-addition structure and 63.9% of the polymer backbone units were in trans-configuration.     

Some aspects of nitroxide-mediated living radical polymerization of N-(p-vinylbenzyl)phthalimide

The free radical polymerization of N-(p-vinylbenzyl)phthalimide (VBP) “initiated” with the adduct of 2-benzoyloxy-1-phenylethyl and TEMPO (BS-TEMPO) or TEMPO-terminated polystyrene (PS-TEMPO) in N,N-dimethylformamide (DMF) at 125 °C was found to proceed in a living fashion, providing low-polydispersity PVBP and block copolymers of the type PS-b-PVBA, where TEMPO is 2,2,6,6-tetramethylpiperidinyl-1-oxy. Unlike TEMPO-mediated styrene polymerization, the polymerization rate slightly but distinctly depended on the adduct concentration, which was interpretable as a pre-stationary behavior. The hydrolysis of those polymers gave poly(p-aminomethylstyrene) (PAMS) and PS-b-PAMS, and further treatment of the block copolymer with hydrogen chloride provided an amphiphilic block copolymer. The polymeric amphiphile was used as an emulsifier in emulsion polymerization to produce a positively charged polymeric microsphere.     

Graft copolymerization of methyl methacrylate on polystyrene backbone through nitroxide-mediated photo-living radical polymerization

Polystyrene-graft-poly(methyl methacrylate) (PSt-graft-PMMA) was prepared by the nitroxide-mediated photo-living radical polymerization using poly(4-vinylbenzyl-4-oxy-2,2,6,6-tetramethylpiperidine-1-oxyl-ran-styrene) (P(VTEMPO-r-St)) as the macromediator. The bulk polymerization of methyl methacrylate was performed at room temperature by irradiation using a high-pressure mercury lamp with P(VTEMPO-r-St) as the mediator having the molar ratio of VTEMPO/St unit = 0.40/0.60 and the molecular weight of Mn = 21,700 and the (2RS,2′RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator in the presence of the (4-tert-butylphenyl)diphenylsulfonium triflate as the photo-acid generator. The polymerization proceeded via a controlled polymerization mechanism because both the first-order time-conversion plots and the conversion-molecular weight plots showed linear increases. It was found that all the VTEMPO units supported the controlled PMMA chains by ¹H NMR analysis because the molar ratio of the VTEMPO at the terminal chain end to the 1-cyano-3-methoxy-1,3-dimethylbutyl group at the initiation chain end of the PMMA was unity.     

Ferrocene polymers. synthesis and polymerization of p-ferocenecenylphenylacetylene

To investigate the influence of the ferrocenyl residue on the reactivity of phenylacetylene towards polymerization and on the properties of polyphenylacetylene, p-ferrocenylphenylacetylene has been synthesised and then polymerized with initiation by free radicals. Theoretical studies on the reactivity of p-ferrocenylphenylacetylene showed good agreement with the observation that the reactivity of this monomer is lower when compared to that of ferrocenylacetylene. The polymers synthesised showed good thermal stability     

Grafting copolymerization of vinyl monomers on polyimide macroinitiators by the method of atom transfer radical polymerization

Graft copolymers with the main polyimide chain and side chains of poly(n-butyl acrylate), poly(tert-butyl acrylate), poly(methyl methacrylate), poly(tert-butyl methacrylate), polystyrene, and polystyrene-block-poly(methyl methacrylate) were synthesized by atom transfer radical polymerization on the multicenter polyimide macroinitiators in the presence of the halide complexes of univalent copper with nitrogen-containing ligands. Polymerization of metha-crylates is most efficiently developed on the polyimide macroinitiators. The obtained graft copolymers initiate the secondary polymerization (“post-polymerization”) of methyl methacrylate. The conditions of detachment of side chains of graft polymethacrylates that do not involve the ester groups of their monomeric units were found. The molecular mass characteristics of the graft copolymers and isolated polymers, being the detached side chains of the copolymers, were determined. The detached side chains of different chemical structures have low values of the polydispersity index. The procedure developed was used for the preparation of new graft polyimides with side chains of poly-4-nitro-4′-[N-methylacryloyloxyethyl-N′-ethyl]amino-azobenzene that cause the nonlinear optical properties and with the side chains of poly(N,N-dimethylaminoethyl methacrylate) that cause the thermosensitive properties of the copolymers.     

Transfer to benzoyl peroxide during the polymerization of p-methoxystyrene

Transfer to benzoyl peroxide is pronounced in the polymerization of p-methoxystyrene (MOS) at 60°. The process is responsible for the low molecular weights of polymers formed when the peroxide is used as initiator; there is no evidence for a non-radical polymerization of the type found with N-vinylcarbazole and the peroxide. Data on the reactivity of MOS towards the benzoyloxy radical and the copolymerization of MOS with methyl methacrylate are presented.     

Kinetics of the potassium persulfate-initiated inverse emulsion polymerization of sodium acrylate solutions

The kinetics of the K₂S₂O₈-initiated inverse emulsion polymerization of aqueous sodium acrylate solutions in kerosene with Span 80 as the emulsifier has been studied. The conversion-time curves are S-shaped. The following expressions have been obtained for the maximum rate of polymerization and the molecular weight of the polymers under the experimental conditions investigated: R_max ∞ [K₂S₂O₈]^0.78[sodium acrylate]^1.5[Span 80]^0.1, (OVERLINE)M(/OVERLINE)_u ∞ [K₂S₂O₈]^−0.37[sodium acrylate]^2.9[Span 80]^−0.2. The activation energy for the maximum rate of polymerization is 94.8 kJ mol^−1. The results suggest a monomer–droplet–nucleation mechanism for the system studied. © 1996 John Wiley & Sons, Inc.     

Diffusion-controlled rate constant of termination reaction in radical polymerization

Smoluchowski's theory has been modified and the improved theory was applied to diffusion-controlled polymerization. This application proved that the rate-controlling process is not transrational diffusion but the segmental diffusion. The segmental diffusion-controlled rate constant was derived by the collision theory. This rate constant explains the experimental fact that the diffusion-controlled rate constant of bimolecular termination in radical polymerization of alkyl methacrylate is inversely proportional to solution viscosity and independent of the molecular weight of the polymeric free radical.     

Living radical copolymerization of styrene/maleic anhydride

Styrene/maleic anhydride (MA) copolymerization was carried out using benzoyl peroxide (BPO) and 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO). Styrene/MA copolymerization proceeded faster and yielded higher molecular weight products compared to styrene homopolymerization. When styrene/MA copolymerization was approximated to follow the first‐order kinetics, the apparent activation energy appeared to be lower than that corresponding to styrene homopolymerization. Molecular weight of products from isothermal copolymerization of styrene/MA increased linearly with the conversion. However products from the copolymerization at different temperatures had molecular weight deviating from the linear relationship indicating that the copolymerization did not follow the perfect living polymerization characteristics. During the copolymerization, MA was preferentially consumed by styrene/MA random copolymerization and then polymerization of practically pure styrene continued to produce copolymers with styrene‐co‐MA block and styrene‐rich block. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2239–2244, 2000