A kinetic study of butyl acrylate free radical polymerization in benzene solution

The free radical polymerization of butyl acrylate has been studied in benzene solutions ranging from 1 to 5 mol·L^–1 at 50°C using 2,2′‐azobisisobutyronitrile as initiator. Under the conditions of our experiments, both the effective rate coefficient for initiation, 2 f k_d , and the coupled parameter, k_p/k_t^1/2, (where k_p and k_t are the constants for propagation and termination reactions, respectively) are dependent on the monomer concentration. The 2 f k_d value shows little increase with monomer concentration. The variation of the k_p/k_t^1/2 parameter has been correlated with the chain length dependence of the termination rate coefficient. This effect is also responsible for the high dependence of the overall polymerization rate, R_p, onthe monomer concentration (1.49).     

Emulsion copolymerization of styrene and butyl acrylate with itaconic acid

The emulsion copolymerization of styrene with itaconic acid and butyl acrylate with itaconic acid (methylenesuccinic acid), initiated by a redox system in the presence of a nonionic emulsifier, was studied at 40°C. Examination of the influence of itaconic acid on the copolymerization with both monomers showed that the presence of itaconic acid had a negative influence on copolymerization conversion and on the rate of copolymerization. the reaction order with respect to itaconic acid is ?0,34 for the copolymerization of itaconic acid with styrene and ?1,40 for its copolymerization with butyl acrylate. In the case of the copolymerization with styrene, itaconic acid has no effect on particle number concentration and particle size. Itaconic acid participates in particle nucleation during its copolymerization with butyl acrylate. Formation of oligomeric radicals in the water phase led to a decreasing number of particles and to increasing particle size.     

A kinetic study of free-radical copolymerization of butyl acrylate with methyl methacrylate in solution

Free-radical copolymerization at 50°C of butyl acrylate with methyl methacrylate was carried out in benzene solution using 3 and 5 mol/L as the overall concentration of monomers. Both the reactivity ratios and the rate coefficients of copolymerization are affected by the total monomer concentration. Reactivity ratios were analyzed on the basis of the “bootstrap” model, and the copolymerization rate is interpreted assuming a penultimate effect upon the propagation reaction.     

Studies on the copolymerization of acrylonitrile with butyl acrylate,vinylidene dichloride,and styrene

Copolymer composition studies are reported, for different mole fractions of acrylonitrile (AN), butyl acrylate (BA), vinylidene dichloride (CV), and styrene (S) in the initial monomer mixture. A partial azeotropy of acrylonitrile was found.     

High-pressure free-radical copolymerization of ethene and butyl acrylate

The free-radical copolymerization of ethene and butyl acrylate was studied between 130 and 225°C at pressures from 1 500 to 2 500 bar. The reactions which were induced either thermally or laser-photochemically were run in two types of continuously operated devices. Reactivity ratio data referring to ethene-rich monomer mixtures are presented. These data allow to estimate the copolymer composition in ethene/butyl acrylate copolymerizations carried out in a wide range of temperatures and pressures.     

Emulsion copolymerization of vinyl chloride with butyl acrylate

The emulsion copolymerization of vinyl chloride and butyl acrylate initiated by ammonium peroxodisulfate at 60°C in the presence of an anionic emulsifier was investigated. Random copolymers of butyl acrylate and vinyl chloride covering several sets of monomer compositions were synthesized by emulsion copolymerization conducted to both low and high conversions. The rate of butyl acrylate polymerization at medium conversion was found to be proportional to the 0,5 and 1,0 power of the butyl acrylate concentration for the system with and without vinyl chloride. The overall rate of poymerization was found to decrease with increasing vinyl chloride concentration in the monomer feed. The particle size increases with increasing vinyl chloride monomer concentration in the monomer feed and conversion. The decrease in molecular weight of butyl acrylate/vinyl chloride copolymer is accompanied with the incease of vinyl chloride concentration in the monomer feed and of conversion. The results are discussed in terms of radical desorption, particle nucleation and the dependence of the equilibrium monomer concentration on the reactor pressure.     

Emulsion copolymerization of acrylonitrile and butyl acrylate, 2. Effect of a radical scavenger on the rate of copolymerization and the copolymer composition

Random copolymers of acrylonitrile and butyl acrylate, covering two sets of compositions, are synthetized by emulsion copolymerization conducted to both low and high conversions. The copolymer formed at low conversion is enriched with acrylonitrile. Addition of a small amount of hydroquinone, however, suppresses the formation of copolymer enriched with acrylonitrile, i.e., the formation of copolymer more homogeneous in composition is favoured. Moreover, the effect of a radical scavenger on the kinetic parameters of the emulsion copolymerization is analyzed. In the presence of a small amount of hydroquinone the molecular weight of copolymer is somewhat increased when compared with that prepared without hydroquinone. In addition, the rate of copolymerization unexpectedly decreases with increasing emulsifier concentration. It is supposed that the recipe ingredients themselves and their reaction products or/and intermediates participate in termination reactions within the monomer swollen polymer particles and probably within the emulsified monomer droplets. The initiation of the emulsion copolymerization of acrylonitrile and butyl acrylate is a two-step process. The first step starts in the aqueous phase by the primary radicals from the water-soluble initiator and acrylonitrile. The second step occurs in the monomer-swollen emulsifier micelles by water-soluble and -insoluble radicals (primary and macroradicals) and by radicals derived from the recipe ingredients.     

Solvent effects on the free-radical copolymerization of butyl acrylate with methyl methacrylate

Free-radical copolymerization of butyl acrylate with methyl methacrylate was carried out at 50°C in a 3 mol/L benzonitrile solution. Differences between the apparent reactivity ratios determined in this work with those previously reported in bulk, toluene and benzene indicate noticeable solvent effects. This fact can be explained through different models, but independent of the chemistry of the system, to obtain the same copolymer composition in bulk or in solution, the monomer feed that should be used is determined by solvent polarity.     

Solvent effect in radical copolymerization of styrene with p-aminostyrene

p-Aminostyrene ( 1 , M₁) and styrene (M₂) were radically copolymerized at 60°C in various solvents. There is a significant solvent effect on monomer reactivity ratios, especially on r₁, suggesting a specific interaction between the solvent and the polymer radical with the p-aminostyrene moiety at the terminal position. In order to clarify the solvent factor influencing the relative reactivity, the hydrogen-bond-accepting basicity of the solvent (β) was determined from enhanced UV shifts for 1 relative to N,N-dimethyl-p-aminostyrene. Regression analysis of r₁ with the solvatochromic parameters revealed that β is the major factor responsible for r₁-variations.     

Decay of radical initiators in emulsion copolymerization of unsaturated polyesters and styrene

Emulsion copolymerization of unsaturated polyesters (UP) with styrene was initiated by potassium peroxodisulfate and by azodiisobutyronitrile (AIBN). The decay rates of both initiators were compared and influences of temperature, electrolyte and concentration of the reaction components studied. Initiation radicals from the persulfate partly add to unsaturated UP units and decarboxylate terminal acid groups of the UP. Initiation by AIBN predominantly occurs in the aqueous phase, and side reactions with this initiator are neglectable.     

Living radical polymerization of styrene and its block copolymerization with methyl methacrylate

The existence of living polymer radicals in emulsion polymerization with a macromolecular heterogeneous initiator has been ascertained by preparing block copolymers of styrene with methyl methacrylate. Polymerization of styrene initiated by oxidized polypropylene and triethylenetetramine (3,6-diaza-1,8-octanediamine) proceeds even after the removal of the initiator from the emulsion, reaches 100% conversion, and methyl methacrylate newly added to the system undergoes further polymerization. The molecular weight of polystyrene and of the block copolymer increases with the conversion. The yield of pure block copolymer is about 90% under optimal conditions. The turbidimetric titration curve of the block copolymer shows a characteristic plateau region and suggests monodispersity of the copolymer. Reasons for the absence of termination in this system are presented. This type of living radical polymerization offers some advantages for the preparation of block copolymers, as compared with the anionic living polymerization.     

ZnCl2 complexes of para-substituted phenyl methacrylates in radical copolymerization with styrene

Copolymerization of phenyl methacrylate, p-tolyl methacrylate, and p-chlorophenyl methacrylate with styrene was carried out in the absence and in the presence of ZnCl₂. It was found by ¹³C NMR, ¹H NMR, and IR spectroscopy that complexes of zinc chloride with the corresponding methacrylates are formed. Reactivity ratios as well as Q and e values for the monomers and complexes were calculated. A correlation between e values and ¹³C chemical shift of the vinyl group of monomers and complexes with ZnCl₂ was found.     

Batch emulsion copolymerization of butyl acrylate and methyl methacrylate in the presence of sodium dodecyl sulfate

Kinetics of batch emulsion copolymerization of butyl acrylate (BuA) with methyl methacrylate (MMA) have been investigated using sodium dodecyl sulfate as emulsifier and the redox system potassium peroxodisulfate (K₂S₂O₈)/sodium disulfite (Na₂S₂O₅) as initiator. Latexes have been characterized with regard to their copolymer composition through ¹H NMR analysis and particle size distribution by a quasi-elastic light scattering (QELS) technique or transmission electron microscopy. The effect of the monomer feed composition on the average copolymer composition vs. conversion was first studied in order to derive emulsion reactivity ratios. However, simulation of experimental data based on monomer partitioning (due to the high water solubility of MMA) and particle swelling was better accounted for when considering bulk reactivity ratios together with polymerization in the aqueous phase (in addition to that in the main locus of the polymer particles). Then, the influence of several pertinent parameters, such as emulsifier concentration, amount of initiator, monomer-to-water ratio and addition of an organic solvent has been examined in relation to the actual polymerization mechanism.     

Infrared spectra and sequence length distribution in free radical styrene/methacrolein copolymers

The method of azoisobutyronitrile (AIBN)-initiated bulk copolymerization of styrene (S) and methacrolein (M) was employed to determine the monomer reactivity ratios r_S = 0.15 and r_M = 0.55 (Q_M = 1.50, e_M = 0.78). Quantitative IR spectroscopy in the region of 4000–450 cm^?1 was used to elucidate the structure of copolymers. In addition to methacrolein units containing aldehyde groups, the copolymers may also contain cyclic hemiacetal structures formed by the reaction of the carbonyls of the neighboring methacrolein units. The carbonyl absorption at 1722 cm^?1 showed that, up to 30 mole-% methacrolein in the copolymer, almost all methacrolein units have free aldehyde groups. The number of cyclic structures increases with the concentration of methacrolein in the copolymer. The experimental data are in agreement with the statistical theory on the sequence length distribution. The shift of the styrene band at 540 cm^?1 to higher wavenumber was investigated and related to the shortening of sequence length of the styrene units. The intensity of the styrene band at 760 cm^?1 was related with the distribution of the MSM triads and the copolymer structure.     

Measurement of conversion in free radical copolymerization from dilatometric data

In order to evaluate copolymerization rates from dilatometric measurements, the relationship between volume contraction and conversion (dilatometric constant) must be investigated. This can be done gravimetrically or by means of density measurements. In cases where one of the monomers is not able to homopolymerize, both methods lead to different values. Equations necessary for this evaluation were derived and verified in the systems diethyl maleate-methyl methacrylate and diethyl maleate-styrene. In some cases, the dependence of the dilatometric constant on feed composition may be predicted taking into account the contributions to volume contraction of the different bond types present in the copolymer. An expression was derived for describing this dependence in cases where one of the monomers does not homopolymerize. Its validity for the system diethyl maleate-styrene was experimentally verified.     

Asymmetric induction in the radical copolymerization of mono and di-l-menthyl fumarate with styrene

Radical copolymerizations of mono- and di-l-menthyl fumarate ( 1 and 2 ) with styrene (St) were carried out, and the copolymers were hydrolyzed with potassium hydroxide. The products show still optical activity even after the removal of the optically active side chain, because of an introduction of asymmetry into the main chain of the copolymer. The specific rotation per one of the diad sequences of hydrolyzed poly( 1 -co-St) was the same as that of hydrolyzed poly( 2 -co-St). The mechanism of asymmetric induction and the position of the new asymmetric center are discussed based on the measurements of UV spectra, optical rotation, and circular dichroism.     

Kinetics of the free radical copolymerization of diethyl maleate with methyl methacrylate

The kinetics of the free radical copolymerization of diethyl maleate (M₁) with methyl methacrylate (M₂) was studied in bulk at 60°C with azoisobutyronitrile (AIBN) as initiator. The reactivity ratios of the system were determined by means of ¹H NMR spectroscopy. The obtained values show that diethyl maleate is not only unable to homopolymerize (r₁₂ = 0) but also display a very low tendency to incorporate in the polymer chain (r₂₁ = 370) under the present conditions. Molecular weight measurements showed that a normal, although very slow growth reaction involving diethyl maleate takes place. Therefore, chain transfer could be neglected in the kinetic analysis. The dependence of the initiation rate constant on the monomer feed was analysed by means of the inhibition method. An equation for describing the observed dependence of polymerization rate on feed composition was derived taking into account the influence of solution viscosity on the termination rate constant (diffusion theory).