Prediction of polymer composition in batch emulsion copolymerization

Monomer partitioning in emulsion copolymerization plays a key role in determining composition drift and polymerization rates. The combination of recently developed thermodynamically based monomer partitioning relationships with mass balance equations, makes predictions of monomer partitioning in emulsion copolymerizations possible in terms of monomer mole fractions and monomer concentrations in the particle and aqueous phases. Using this approach, the effects of monomer to water ratios and polymer volumes on the monomer mole fraction within the polymer particle phase in a nonpolymerizing system at thermodynamic equilibrium can be determined. Comparison of these monomer partitioning predictions with experiments for the monomer system methyl acrylate—vinyl acetate shows good agreement. Furthermore, composition drift occurring in a polymerizing system as a function of conversion can be predicted if the assumption is made that equilibrium is maintained during reaction. Comparison of predictions with experimental results for emulsion copolymerizations of the monomer systems methyl acrylate—vinyl acetate and methyl acrylate—indene shows good agreement. © 1994 John Wiley & Sons, Inc.     

Automated batch emulsion copolymerization of styrene and butyl acrylate

This article describes a method for carrying out emulsion copolymerization using an automated synthesizer. For this purpose, batch emulsion copolymerizations of styrene and butyl acrylate were investigated. The optimization of the polymerization system required tuning the liquid transfer method, sufficient oxygen removal from the reaction medium and setting a proper sampling procedure. The monomer conversion‐time plots obtained with gas chromatography revealed a good reproducibility of the automated reaction kinetics. Furthermore, the particle size distributions and the properties of the final products were found to be highly reproducible. The performance of the automated reactions was subsequently compared with the conventional ones: similar reproducibility of either synthetic method was observed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Calorimetric monitoring of emulsion copolymerization reactions

An approach for monitoring both the overall conversion and the cumulative copolymer composition in emulsion copolymerization systems via calorimetric measurements was developed. The approach was checked by carrying out batch emulsion copolymerizations of methyl methacrylate/n-butyl acrylate, n-butyl acrylate/vinyl acetate, and methyl methacrylate/vinyl acetate and comparing calorimetric based estimations with off-line determinations of both the overall conversion and the cumulative copolymer composition. A good agreement was achieved for most of the cases studied. © 1993 John Wiley & Sons, Inc.     

Composition control of copolymer in semibatch emulsion copolymerization. II. MMA/styrene/BMA three‐component system

In this study, polymers of the MMA/Styrene/BMA three‐component system were synthesized through either soapless semibatch emulsion copolymerization or soapless batch emulsion copolymerization technique. The optimal monomer feed flow rate was determined from the interphase partition laws, monomer reactivity ratios, and three or four times of iterative experimental procedures through semibatch emulsion copolymerization. As a result, the instantaneous composition of polymers could also be effectively controlled to get the desired final products. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3253–3269, 2000     

Emulsion co- and terpolymerization of styrene,methyl methacrylate,and methyl acrylate. I. Experimental determination and model prediction of composition drift and microstructure in batch reactions

In Part I of this series the reactivity ratios of the comonomer pair methyl acrylate-methyl methacrylate were determined with low-conversion bulk polymerizations. It was shown that the binary reactivity ratios of the systems styrene-methyl acrylate, styrene-methyl methacrylate, and methyl acrylate-methyl methacrylate describe composition drift in low-coversion bulk terpolymerizations with these monomers reasonably well. A computer model was developed to simulate the composition drift in emulsion co- and terpolymerizations. The composition drift in two batch emulsion copolymerization systems (styrene-methyl acrylate and methyl acrylate-methyl methacrylate) and one emulsion terpolymerization system (styrene-methyl acrylate-methyl methacrylate) was investigated both experimentally and with the model. Experimental results were compared with model calculations. The copolymer chemical composition distributions (CCD) were determined with gradient polymer elution chromatography (GPEC®). This technique was also used for the first time to obtain information about the extent of composition drift in emulsion terpolymerizations. Cumulative terpolymer compositions were determined with ³H-NMR as a function of conversion and with this information the three-dimensional CCD was obtained. The composition drift was analyzed with respect to free radical copolymerization kinetics (reactivity ratios) and monomer partitioning. It was shown that in most emulsion copolymerizations the composition drift is mainly determined by the reactivity of the monomers and to a lesser extent by monomer partitioning, except in systems where there is a large difference in water solubility. The model predictions for cumulative terpolymer composition as a function of conversion and the three-dimensional terpolymer CCD showed excellent agreement with the experiments. The GPEC® elution chromatogram of the terpolymer was found to be in accordance with the predicted CCD and the experimentally determined CCD. © 1996 John Wiley & Sons, Inc.     

Ethylene-vinyl acetate semi-batch emulsion copolymerization: Use of factorial experiments for process optimization

The application of factorial experiments to optimize the ethylene-vinyl acetate emulsion polymerization process is described herein. A prior extensive experimental phase identified those variables that are most important for ethylene-vinyl acetate emulsion copolymer production. The effects of temperature, pressure, added co-solvent, vinyl acetate feed rate and emulsifier type, and concentration on the rate of polymerization, cumulative copolymer composition, molecular weight averages, and particle size and number are described in this article. The primary objectives of this research were to increase the amount of ethylene that could be incorporated into the copolymer at reduced temperatures and pressures (our target was a copolymer with an ethylene content of 30% by weight at 500 psig and 20°C versus the commonly employed industrial conditions in excess of 1000 psig), to achieve an improved process understanding, and to accumulate reliable data for modelling purposes. A copolymer containing 34% by weight of ethylene has been achieved at a pressure of 500 psig and a temperature of 20°C. The confusion present in the literature surrounding emulsifier effects has also been clarified. A discussion of hydrolysis, experimental reproducibility, and glass transition temperatures is also included. The sequential nature of the experimental process is illustrated throughout these optimizing experiments. © 1994 John Wiley & Sons, Inc.     

Ethylene–vinyl acetate semi-batch emulsion copolymerization: Use of factorial experiments for improved process understanding

A good working knowledge of the mechanism and an appreciation of the effects the process variables have on the properties of interest are required for optimization and control of polymerization processes. Despite the importance of ethylene-vinyl acetate emulsion copolymers, limited kinetic information is available. Results from a series of factorial experiments are presented here which examine the emulsion polymerization of ethylene with vinyl acetate. Copolymers of up to 32 wt % ethylene have been produced at an ethylene pressure of 500 psig and a temperature of 20°C. The effects of the process variables on the rate of polymerization, copolymer composition, particle size and number, molecular weight averages, and gel content are discussed. The kinetic results obtained suggest process improvements for the production of homogeneous copolymer. Mechanistically, the locus of polymerization has been verified as the polymer particles and little water phase polymerization was observed. © 1993 John Wiley & Sons, Inc.     

Ethylene–vinyl acetate semi-batch emulsion copolymerization: Experimental design and preliminary screening experiments

Ethylene–vinyl acetate emulsion copolymers are useful materials for paint, adhesive, and coating applications. The kinetics of their production remain largely unstudied, probably due to the inherent difficulties associated with pressure polymerizations. Polymerizations at elevated pressures are in general more difficult to understand and control, and relatively more expensive since one has to consider the added cost of increased safety precautions. Reported here are the preliminary results of an extensive experimental investigation of the variables which govern the ethylene–vinyl acetate emulsion process. Two redox initiator systems have been identified as more suitable for the polymerization process. Two buffer systems, namely sodium acetate/acetic acid and potassium phosphate, have been used to effectively control pH. The addition of n-hexane has offered an effective method of enhancing the ethylene content in the copolymer produced. Several other important variables including agitation/mixing and emulsifier type and concentration have been identified and are discussed. These screening experimental observations have aided in the selection of suitable design levels for future, more focused experimentation to quantify the effects of reaction variables on the latex and copolymer properties of interest. A review of the existing literature on ethylene–vinyl acetate copolymer properties and processes is also included. © 1993 John Wiley & Sons, Inc.     

过硫酸铵-亚硫酸氢钠引发活化淀粉与丙烯酰胺反相乳液聚合动力学研究

以过硫酸铵-亚硫酸氢钠作为氧化还原引发剂,研究了经球磨活化的淀粉与丙烯酰胺在反相乳液体系中的接枝共聚反应动力学,分别考察了反应温度、引发剂浓度、淀粉浓度、单体浓度、乳化剂用量对接枝速率的影响.结果表明,在实验考察范围内的动力学关系式为:Rp∝[(NH4)2S2O4)]0.571[NaHSO3]0.571[St]0.59...     

Synthesis and emulsion copolymerization of amphiphilic poly(2-oxazoline) macromonomer possessing a vinyl ester group

The present article describes the synthesis and emulsion copolymerization of a block-type amphiphilic poly(2-oxazoline) macromonomer possessing a polymerizable vinyl ester group. The macromonomer was synthesized by one-pot two-stage block copolymerization of 2-oxazolines using vinyl iodoacetate as initiator. 2-Methyl- and 2-n-butyl-2-oxazolines were employed for the construction of hydrophilic and hydrophobic segments, respectively. The surface activities evaluated by the surface tension of the macromonomer in water were fairly good. Emulsion copolymerization of vinyl acetate with the macromonomer was carried out. The macromonomer acted as a polymeric surfactant, as well as a comonomer. The resulting copolymer latex particles were spherical and their diameter was in the sub-micron range. The effects of the composition of the macromonomer on the emulsion copolymerization and the resulting latex particles were examined. © 1993 John Wiley & Sons, Inc.     

Emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonate

The kinetics of the emulsifier-free emulsion copolymerization of styrene and sodium styrene sulfonate have been examined over a range of comonomer compositions. The rate of polymerization was found to increase dramatically in the presence of small amounts of sodium styrene sulfonate. This increase is attributed to the increased number of particles formed when sodium styrene sulfonate was present and to a gel effect enhanced by ion association. At low concentrations of functional comonomer, where a monodisperse product was obtained, a homogeneous nucleation mechanism of particle generation is proposed. At higher concentrations, broader and then bimodal size distributions were obtained, and this is ascribed to significant aqueous phase polymerization of sodium styrene sulfonate. The water-soluble homopolymer is supposed to act as a locus of polymerization. The occurrence of this aqueous phase side reaction and the generation of secondary particles makes impossible the preparation of highly sulfonated polystyrene latexes by batch or seeded batch emulsion copolymerization.     

反应性乳化剂存在下半连续苯丙乳液共聚合表观动力学

研究了在反应性乳化剂SE-10N存在下,采用半连续滴加工艺进行苯丙乳液共聚合的表观动力学.首先利用间歇法研究了引发剂、乳化剂用量、单体总量和温度对聚合反应速率的影响,得到了相应的聚合反应速率方程为Rp =k[M]0.30[I]0.18[E]0.97,并计算得到聚合反应的表观活化能为90.8 kJ·mol-1.然后采用半连续滴加法,讨论了不同滴加速率对聚合表观速率Rp的影响,结果表明,随滴加速率Ra 的增加,反应速率Rp也增加,但增加的幅度逐渐减少,且聚合过程的状态不断远离饥饿态.要使该聚合过程的状态保持在稳定的饥饿态,单体滴加时间应控制在140 min 以上.     

Emulsifier-free emulsion copolymerization of styrene and sodium 1-allyloxy- 2-hydroxypropane sulfonate

Colloidal particles of poly(styrene-co-sodium 1-allyloxy- 2-hydroxypropane sulfonate) with diameters of 508 ∼ 596 nm were synthesized by emulsifier-free emulsion copolymerization, crosslinked with divinylbenzene, and initiated by potassium persulfate/sodium bisulfite in a mixed solvent of water and acetone. The diameters of the submicrometer-sized particles were measured by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The surface charge densities of the particles were determined by condutometric titration. The results showed that the highly surface charged monodispersed submicrometer-sized particles were obtained by two-stage shot growth polymerization. The particle diameters could be reduced and controlled by adding suitable amount of acetone.     

Effect of the number of seed polymer particles on the kinetic behavior of the seeded emulsion copolymerization of styrene and acrylamide

The seeded emulsion copolymerizations of styrene and acrylamide were carried out at 50°C using polystyrene latex particles as the seed and potassium persulfate as the initiator, respectively. It was found that the change in the number of seed particles initially charged causes a drastic change in the kinetic behavior of this seeded emulsion copolymerization system: when the number of seed particles initially charged was less than a certain critical value, both styrene and acrylamide started polymerization from the beginning of the reaction. However, when the number of seed particles was higher than this critical value, an apparent induction period suddenly emerged only for acrylamide polymerization, that is, acrylamide did not start polymerization until the styrene conversion exceeded around 75%, while the styrene polymerization started and continued very smoothly from the beginning of the reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2689–2695, 1997     

Novel emulsion graft copolymerization onto the silylmethyl group of poly(dimethylsiloxane)

The influence of radical initiators upon the emulsion graft copolymerization of styrene and acrylonitrile onto poly(dimethylsiloxane) (PDMS) was studied. As initiators, a series of peroxides and hydroperoxides were coupled with ferrous sulfate, among which the tert-butyl peroxylaurate system gave the highest grafting efficiency (30%). The tert-butyl peroxylaurate initiator fulfills the criteria for efficient radical grafting by generating only the tert-butoxy radical, which is reluctant to form a carbon radical via β-scission, being highly hydrophobic, and not carrying a tertiary hydrogen that may be abstracted by a radical. ¹³C-NMR analysis of the products showed that the grafting occurred on the silylmethyl groups of PDMS to give 10–25 grafts per polymer and graft ratio in the range 44–140%. The PDMS graft copolymers thus obtained could be used as surface-modifying agents to improve the lubricity and water-repellency of ABS [poly(styrene-co-acrylonitrile)-graft-polybutadiene]. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2607–2617, 1997     

The effect of water solubility of the monomers on composition drift on methyl acrylate-vinyl ester combinations

It has been shown theoretically that composition drift mainly depends on reactivity ratios and water solubilities. Minimum composition drift can be obtained by lowering the monomer-to-water ratio in monomer systems where the more reactive monomer is also the more water-soluble one. Investigating the effect of water solubility on composition drift while keeping the reactivity ratios constant can elucidate the importance of the water solubility. The monomer combinations methyl acrylate-vinyl acetate (MA-VAc), methyl acrylate-vinyl 2,2-dimethylpropanoate (MA-VPV), and methyl acrylate-vinyl 2-ethylhexanoate (MA-V2EH) are ideal monomer combinations for studying the effect of water solubility on composition drift since the reactivity ratios for this series of monomer systems are approximately equal. Solution copolymerizations are performed to elucidate maximum composition drift at extremely high monomer-to-water ratios. From comparing theoretical predictions with experimental results it could be concluded that composition drift for the monomer combination MA-VAc could only be reduced since the difference in water solubility was not large enough to compensate the effects of the large difference in reactivity ratios. However, for the monomer combinations MA-VPV and MA-V2EH the difference in water solubility was large enough to make minimum composition drift possible for low monomer-to-water ratios even for monomer combinations with reactivity ratios as far apart as in the MA-vinyl ester case. © 1996 John Wiley & Sons, Inc.     

Model for the prediction of separation profile of oil-in-water emulsion

This paper proposed a model that explains the separation mechanism of oil-in-water emulsion taking into account both creaming and coalescence processes. Oil-in-water emulsion separation experiments were performed in a batch separator using kerosene and distilled water. The predictions of the proposed model agreed well with the experimental results as well as previously published experimental data. The comparison between the proposed model and the previously published model showed that the proposed model has higher accuracy in predicting the separation profile of oil-in-water emulsion, with an accuracy of within 10%. Thus the proposed model gives better representation of the oil-in-water emulsion separation process.     

Graph-theoretic approaches for qualitative analysis and numerical solution of equations of multicomponent copolymerization

An original algorithm for practical realization of the approaches formulated in terms of the graph theory to calculate the dynamics of multicomponent copolymerization has been developed. The employment of such an algorithm provides a possibility to extend the range of copolymerization processes (normally calculated using an ordinary personal computer), bringing the number of the components up to 10, whereas formerly this number did not exceed 5. It has been demonstrated how, upon minor modification, the above algorithm can be employed to find the location of the stationary points of multicomponent copolymerization equations as well as to determine the type of each such a point. © 1996 John Wiley & Sons, Inc.     

Preparation of polymer/silica composite nanoparticles bearing carboxyl groups on the surface via emulsifier‐free emulsion copolymerization

Polymer/silica organic/inorganic composite nanoparticles bearing carboxyl groups on the surface were prepared via the emulsifier‐free emulsion copolymerization of methyl methacrylate and sodium methacrylate (NaMA). Carboxyl groups were generated by the addition of hydrochloric acid at the end of the copolymerization. Two methods of NaMA addition were studied: batch and two‐stage procedures. The batch procedure allowed only a limited number of carboxyl groups to effectively bond to the composite nanoparticles. In contrast, the number of carboxyl groups could be altered over a wide range with the two‐stage procedure. Fourier transform infrared spectroscopy and chemical titration were independently used to quantify the number of carboxyl groups, giving values close to each other and to the feed. A kinetic study indicated that the copolymerization followed a mechanism different than that found earlier. The average size of the composite nanoparticles was approximately 40 nm, as measured by both transmission electron microscopy (TEM) and laser scattering, and their polydispersity index was close to 1, indicating a fairly narrow size distribution. TEM photographs of the composite nanoparticles showed a multilayered core–shell structure with one silica bead as the core and with poly(methacrylate acid) as the outmost shell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2826–2835, 2005