Inverse Emulsion Polymerization Of Acrylamide Research Articles

Theoretical and experimental investigations of the inverse emulsion polymerization of acrylamide

ABSTRACTIn this study, the inverse emulsion polymerization modeling of polyacrylamide with population balance equations (PBEs) was performed. The PBEs were derived on the basis of the zero–one kinetic model. The effects of the surfactant steric barrier and surfactant reaction with radicals, including monomeric radicals, on the radical entry rate into the particle were taken into account. In the modified model, the coagulation phenomenon was included through consideration of the effects of forces not included in the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory; these include hydration and steric forces in addition to DLVO forces. The effects of the surfactant and initiator concentrations on the conversion, particle size, and average molecular weight (MW) were investigated by simulation and experimental studies. Increasing the surfactant concentration initially increased the conversion and decreased MW. A further increase in the surfactant concentration resulted in a decrease in the conversion and an increase in MW. The average particle size decreased with an increase in the surfactant concentration. An increase in the initiator concentration led to an increase in the monomer conversion and a decrease in the average MW. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41916.

R-ATRP of Acrylamide under the Action of Iron Complex System in Inverse Emulsion

Reaction of acrylamide in inverse emulsion, adding Fe (EDTA)2-, with ammonium persulfate (APS) to form complex initiation system, Fe (EDTA)2 -is oxidized to Fe (EDTA)-, the control effect of the Fe (EDTA)-in the inverse emulsion polymerization of acrylamide was discussed. The results showed that acrylamide in inverse emulsion polymerization reaction by adding Fe (EDTA)2-, When the complex concentration is 2.8×10-4mol/L, n [(NH4)2S2O8]::n (FeSO4):n (Na2EDTA)=1:1:1.10, the reaction time was 6 hours, the amount of emulsifier is 3%,the reaction temperature is 40°C , The rate of conversion of monomer Increased in linear relationship with molecular weight, the final rate of conversion of monomer was 93.16%;a kinetic curve showed a good linear relationship, the coefficient of linear correlation was 0.997,Therefore, the Fe (EDTA)2 -have dual role firstly as a reducing agent of an oxidation - reduction initiator system and secondly as potential catalyst in reverse atom transfer radical polymerization (RATRP) .

Synthesis and nucleation mechanism of inverse emulsion polymerization of acrylamide by RAFT polymerization: A comparative study

Well-defined poly (acrylamide) is synthesized by RAFT inverse emulsion polymerization using hydrophilic and lipophilic initiators. The kinetic behavior observed for RAFT inverse emulsion polymerization is similar to that for RAFT inverse miniemulsion polymerization. The nucleation mechanism of inverse emulsion polymerization of acrylamide is firstly investigated by RAFT polymerization and verified by GPC and SEM measurements. Droplet nucleation is found to be the primary mechanism in the inverse emulsion polymerization of acrylamide. However, polymerization occurring in the continuous phase is not negligible when lipophilic initiator is used.

On the Kinetics of Inverse Emulsion Polymerization of Acrylamide

The inverse emulsion polymerization of acrylamide (AAm) initiated by a water-soluble initiator (ammonium peroxodisulfate, APS) was investigated. The rate of inverse emulsion polymerization increased with both increasing initiator and emulsifier concentrations. The molecular weight of polyacrylamide decreased with increasing the initiator concentration and slightly rose with increasing the emulsifier concentration. With increasing APS concentration the curves are broader. This indicates widening of molecular weight distribution. The decrease in M¯ w with increasing APS concentration results from the increased termination of growing radicals mainly by primary or oligomeric radicals. The number of radicals per particle was inversely proportional to the APS concentration. The increased deactivation of primary and monomeric radicals decreased their desorption rate and re-entry rates as well. The desorption rate of radicals was interpreted using three models: the Nomura model (Nmodel, k′ des, N), the Gilbert model (Gmodel, k′ des, G) and the Ugelstadt model (Tmodel, k′ des, T). The desorption rate constant (k′ des) for the different models differs by up to two orders of magnitude. The value of k des increases in the following order: Nmodel < Gmodel < Tmodel. The radical entry rate decreases with rising emulsifier concentration and increases with rising initiator concentration.

The synthesis of polyacrylamide nanoparticles in supercritical carbon dioxide

Polyacrylamide nanoparticles, 50 to 200 nm, were created by inverse emulsion polymerization of acrylamide in supercritical carbon dioxide. The cross-linked polyacrylamide was produced by intermolecular imidization.

On the Hybride Inverse-Emulsion Polymerization of Acrylamide

: The free-radical polymerization of acrylamide (AAm) in the inverse water/monomer/cyclohexane/Tween 85 hybride emulsion was investigated. The effect of emulsifier concentration on the rate of polymerization, desorption of radicals, and colloidal parameters was studied. The homogenization of water, AAm, and emulsifier Tween 85 enabled the formation of stable inverse hybride AAm and N,N’ -methylenebis(acrylamide) (MBA) sterically stabilized emulsions. The polymerization rate vs. conversion curve consists of two nonstationary rate intervals. This is attributed to the variation of monomer concentration at the reaction loci with an increasing conversion. The maximal rate of inverse emulsion polymerization of AAm increases with an increase in the nonionic emulsifier (Tween 85) concentration. The addition of a cross-linker (MBA) slightly increases the rate of polymerization. The average number of radicals per particle (n¯) was observed to be much below 0.5 and to slightly increase with increasing particle size and the addition of MBA. The low value of n¯ was ascribed to the effective desorption of transferred monomeric radicals. The strong decrease of the molecular weight of polyAAm with increasing emulsifier concentration is attributed to the participation of emulsifier on the chain transfer events. The independence of the particle size on the conversion strongly supports the monomer droplet nucleation and the miniemulsion polymerization mechanism. The droplet nucleation and the variation of monomer concentration at the reaction loci can induce the nonstationary-rate intervals.

Inverse Emulsion Polymerization of Acrylamide Initiated by Oil- and Water-soluble Initiators: Effect of Emulsifier Concentration

The nature of the reaction loci in inverse emulsion polymerization of acrylamide (AAm) initiated by oil (2,2′-azoisobutyronitrile, AIBN)- and water-soluble (ammonium peroxodisulfate, APS) initiators was investigated. The rate of polymerization (Rp,max, Interval 2) increases with increasing the emulsifier concentration up to a certain critical concentration and then decreases. The rate of polymerization and the polymerization rate per particle are somewhat larger in the APS-initiated polymerization than in the AIBN-initiated one. For both initiators the polymerization rate per particle is proportional to the particle size and decreases with increasing the emulsifier concentration and the decrease is much more pronounced at the high emulsifier concentrations. The similar kinetic dependences for both initiators were discussed in terms of the formation of monomeric or oligomeric radicals with the similar nature, mobility via the reaction system and partitioning between the oil and water phases. The similar radicals carrying the initiator fragment were formed by the addition of one or two (or several) units to the primary radicals (SO4•− or 2-cyanoisopropyl). The estimated average number of radicals per particle (n̅) is much below 0.5. The low radical concentration in the polymer particles was discussed in terms of the desorption of monomeric and emulsifier radicals. The desorption of radicals was confirmed by both the Nomura model (Nmodel, k′des,N) and the Ugelstad approach (the solution of population balance for the particle with n̅, Tmodel, k′des,T). The k′des,T’s were found to be much larger than the k′des,N’s. The differences in the k′des’s were discussed in terms of the desorption (surface active) monomeric radicals (the polymerization within the outer spheres of polymer particles) and emulsifier (the chain transfer to emulsifier) radicals. The radical entry rate decreases with increasing the emulsifier concentration or decreasing the particle size.

Photoinitiated, inverse emulsion polymerization of acrylamide: Some mechanistic and kinetic aspects

AbstractThe kinetics of photoinitiated, inverse emulsion polymerization of acrylamide with 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA) as a photoinitiator was investigated under three different cases. First, in a quartz reactor transparent to full UV light, the polymerization rate (Rp) increased and then decreased with the change of initiator order from 0.27 to a negative value when the DMPA concentration was increased, and it was particularly unusual that monomer orders at different DMPA concentrations were lower than the first. Second, for polymerization without DMPA in a quartz reactor, the dependence of Rp on monomer concentration was similar to that of Rp on initiator concentration in the aforementioned case. Third, when polymerization was carried out in a Pyrex reactor where the far UV light was filtered, a peak rate was also observed, and initiator orders varied from 0.24 to a negative value; however, under this case monomer orders at different initiator concentrations were greater than the first. These results indicated that the effect of absorbance often observed in bulk or solution photopolymerization also existed in this system, and the self‐initiation of monomer had some influence on polymerization, and the role of primary radical termination could not be neglected, as evidenced by kinetic analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 846–852, 2004

Manifestation of Polyacrylamide Inverse-Emulsion Instabilities through Oscillatory Shear

The stability of polyacrylamide-based inverse emulsions, prepared with surfactant blends consisting of mixtures of fatty acid esters, ethoxylated fatty acid esters, and ABA triblock copolymeric stabilizers, was investigated by means of oscillatory shear measurements. “Milky-like” inverse lattices were obtained from inverse-emulsion polymerization of acrylamide. The surfactant blend composition and type were varied at a fixed concentration of 3 wt %, with the elastic modulus followed as a function of time for a period not exceeding 30 days. The data indicated that the logarithm of G‘ as a function of time was linear for at least 15 days. The slope of log G‘ versus time was validated as an index of stability, such that the higher the slope, the less stable the system. A threshold with regard to this indicator was also established at 0.02. As two surfactant types (fatty acid esters and block copolymers) were used to stabilize the emulsion, a threshold stability was also observed as a function of the stabiliz...

The inverse emulsion polymerization of acrylamide using poly(methyl methacrylate)‐graft‐polyoxyethylene as the stabilizer

Inverse emulsion polymerization of an aqueous solution of acrylamide (AM) in toluene is carried out using poly(methyl methacrylate)-graft-polyoxyethylene (PMMA-g-PEO) as an emulsifier. The kinetics of polymerization, morphology of the particle, and particle size of the inverse emulsion have been investigated. The rates of polymerization are found to be proportional to the initiator concentration, the monomer concentration, and the emulsifier concentration. The morphology of particles shows a spherical structure. The mechanism of inverse emulsion polymerization using amphipathic graft copolymer as the emulsifier is proposed. The resulting molecular weights of polyacrylamide are extremely high, and relate to the amphipathic graft copolymer structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 528–534, 2001

The inverse emulsion polymerization of acrylamide using poly(methyl methacrylate)-graft-polyoxyethylene as the stabilizer

Inverse emulsion polymerization of an aqueous solution of acrylamide (AM) in toluene is carried out using poly(methyl methacrylate)-graft-polyoxyethylene (PMMA-g-PEO) as an emulsifier. The kinetics of polymerization, morphology of the particle, and particle size of the inverse emulsion have been investigated. The rates of polymerization are found to be proportional to the initiator concentration, the monomer concentration, and the emulsifier concentration. The morphology of particles shows a spherical structure. The mechanism of inverse emulsion polymerization using amphipathic graft copolymer as the emulsifier is proposed. The resulting molecular weights of polyacrylamide are extremely high, and relate to the amphipathic graft copolymer structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 528–534, 2001

The inverse emulsion polymerization of acrylamide using polystyrene-graft-polyoxyethylene as the stabilizer

Inverse emulsion polymerization of aqueous solution of acrylamide (AM) in toluene is carried out using polystyrene-graft-polyoxyethylene (PSt-g-PEO) as an emulsifier. The kinetics of polymerization, morphology of the particle, and particle size of the inverse emulsion have been investigated. The rates of polymerization are found to be proportional to the initiator concentration, the monomer concentration, and the emulsifier concentration. The morphology of the particle shows a spherical structure. The effects of amphipathic graft copolymer structure on the average molecular weight of polyacrylamide are studied. The mechanism of the inverse emulsion polymerization using amphipathic graft copolymer as emulsifier is proposed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2719–2725, 1999

The inverse emulsion polymerization of acrylamide with pentaerythritolmyristate as emulsifier. 2. Mathematical modelling

A mathematical model of the inverse emulsion polymerization of aqueous acrylamide solutions in isooctane as dispersing media with the chemically pure emulsifier pentaerythritolmonomyristate and an oil-soluble azo initiator has been developed. A Monte Carlo method was used successfully to calculate the kinetics, molar mass averages and average particle sizes. The computation time of the method was reduced by calculating the chain length of the polymer molecules via the life-time of the radicals. It is shown that a few assumptions based on the mirror image of an ideal conventional emulsion polymerization with Smith-Ewart case 2 kinetics are sufficient to comprehensively describe the experimental findings.

The inverse emulsion polymerization of acrylamide with pentaerythritolmyristate as emulsifier. 1. Experimental studies

The inverse emulsion polymerization of aqueous acrylamide solutions in isooctane as dispersing media with the emulsifier pentaerythritolmyristate and an oil-soluble azo initiator was studied, particularly with respect to the influence of the chemically pure emulsifier. In this free radical polymerization, a water-in-oil emulsion with droplet sizes around 10μm is converted into a latex with average particle diameters between 80 and 200nm containing a polymer with molar masses up to 16×106gmol-1 Kinetic data were measured by adiabatic as well as by isothermal calorimetry. The influences of various parameters on polymerization kinetics, particle numbers and molar mass averages were studied. Experimental results show a positive influence of the emulsifier concentration on the reaction rate and indicate the dominance of a bimolecular termination re-action with respect to the polymer radicals above a certain initiator concentration. © 1998 SCI.

Synthesis and kinetics of microgel in inverse emulsion polymerization of acrylamide

The kinetic behavior is studied in inverse emulsion polymerization of acrylamide. The polymerization rate in a micelle is proportional to the monomer concentration and the effective average radical concentration. When concentrations of monomer and radical are too low to proceed the polymerization only, some finite final conversion is obtained. The micelles of various sizes have different effective average radical concentrations at the same monomer concentration. Therefore, the polymerization rate and the final conversion are different for various sized micelles. The minimum amounts of emulsifier required to get stable state during reaction is 10 and 7 wt% (based on oil phase) in toluene and n-heptane systems, respectively. Phase inversion is observed with the increase of viscosity during polymerization. The final latex coagulates obviously in the toluene system even with 10 wt% of emulsifier, however, it can be improved more in the n-heptane system with 10 wt% of emulsifier. The crosslinking agent which copolymerizes with the monomer was supposed to remain in the interface of micelles. Such interfacial copolymerization not only hardens particles but improves the stability of the system also, therefore avoiding coagulation among particles. An increase in the content of crosslinking agent leads to a more uniform size of final particles. The microgel added in the alkyd resin decreases the drying time. The greater the amount of microgel added, the shorter the drying time.

Inverse emulsion polymerization of acrylamide and salts of acrylic acid

Kinetics of the persulfate-initiated inverse emulsion polymerization of acrylamide and acrylic acid sodium and ammonium salt have been investigated. Rate orders with respect to the initiator, the monomers and the emulsifier were determined for all three monomers. Influences of the change of concentration of the individual components of the polymerization system on molecular weight and particle size of the resulting polymers were described. Overall activation energies of polymerizations were determined. Results of the kinetics measurements for the non-ionic acrylamide and the ionic salt of acrylic acid were compared. Dependence of the polymerization rate R p on the concentration of components in the polymerization system can be expressed for all three mononers by the following equation: R p = [ I] 0.5 [M] 1.5 [E] 0.1. These kinetic data are in good agreement with the supposed mechanism of polymerization. The almost sesquimolecular rate order with respect to the monomer proves to the participation of the monomer on the initiation reaction. This fact also explains the reason of the unusually low polymerization temperature of 40 °C. The persulfate-initiated inverse emulsion polymerization of acrylic monomers takes place as a solution polymerization in microparticles.

Polymerization of acrylamide and methylmethacrylate at the surface of submicron polypyrrole particles

AbstractThis paper presents two methods of encapsulation of polypyrrole latex particles of different sizes by an insulating polymer. The first method concerns the encapsulation by inverse emulsion polymerization of acrylamide with crosslinking agent. That method is effective for the smallest particles (about 100 nm). The second method concerns encapsulation by direct emulsion polymerization of methylmethacrylate. Inhibition of polymerization occurs if potassium persulfate is used as the initiator, whereas no inhibition is observed with 4,4′ azobis 4‐cyanopentanoic acid as the initiator. These results are explained in terms of the ion‐exchange capacity of conducting polymers. This second method seems to be effective for all the sizes of polypyrrole particles. These encapsulated particles have been characterized by transmission electron microscopy, scanning electron microscopy, quasi elastic light scattering, cyclic voltametry and electrophoresis. Cyclic voltammetry recently developed on aqueous suspensions of polypyrrole particles was revealed to be the best technique because of its simplicity and speed.

Inverse emulsion polymerization of acrylamide in supercritical carbon dioxide. [Erratum to document cited in CA120:55125

Inverse emulsion polymerization of acrylamide in supercritical carbon dioxide. [Erratum to document cited in CA120:55125

Inverse emulsion polymerization of acrylamide in supercritical carbon dioxide

ADVERTISEMENT RETURN TO ISSUEPREVArticleInverse emulsion polymerization of acrylamide in supercritical carbon dioxideF. A. Adamsky and E. J. BeckmanCite this: Macromolecules 1994, 27, 1, 312–314Publication Date (Print):January 1, 1994Publication History Published online1 May 2002Published inissue 1 January 1994https://doi.org/10.1021/ma00079a049RIGHTS & PERMISSIONSArticle Views1019Altmetric-Citations107LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (394 KB) Get e-Alerts Get e-Alerts

Studies on the kinetics of inverse emulsion polymerization of acrylamide using α-ketoglutaric acid as photoinitiator

The kinetics of the inverse emulsion photopolymerization of acrylamide using the water soluble photoinitiator (triplet radical generator) α-ketoglutaric acid (α-KGA), sorbitan monooleate (Span 80) as the emulsifier and toluene as the oil phase has been studied. The rate of polymerization ( R p) can be represented by: R p ∝ I 0.5[C] 0.5[M] 1.28[E] −0.42, where I, C, M and E represent the light intensity (313 nm u.v. light), photoinitiator, monomer and emulsifier, respectively. The kinetic results suggest that the polymerization of acrylamide is essentially a microsuspension one. The emulsifier apparently acts as a retarder. The overall activation energy is 10.20 ± 1.58 kJ mol −1. The presence of the gel effect is evident from the increase of molecular weight with conversion and also from the nature of the percentage conversion versus time curves. A useful linear relation between high conversion molecular weight and maximum R p was found to exist. The relation yields the upper limit of the viscosity average molecular weight [(7.25 ± 0.48) × 10 6] for 4.5 mol dm −3 acrylamide, 6.3% (w/v) Span 80, toluene:water = 53:47 (v/v), a stirring rate of 425 rev min −1 and a temperature of 30°C.