Particle Formation in Polymer Colloids, III: Prediction of the Number of Particles by a Homogeneous Nucleation Theory

Fitch, Robert M.; Tsai, Chun-An

doi:10.1007/978-1-4684-1920-7_5

Cited by 205 publications

(38 citation statements)

References 20 publications

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“…This theory is indeed a combination of ideas proposed by Fitch et al [39][40][41] and Oganesyan [51] with the difference that the authors consider the surface energy of the particles as an adjustable parameter of the model.…”

Section: Aggregative Nucleation Mechanismmentioning

confidence: 99%

“…According to the hypothesis of the formation mechanism of PMP for homogeneous nucleation [27,[35][36][37][38][39][40][41][42], the formation of particles or macromolecules derived from the radicals who have reached the critical length (j ), where they lose solubility and precipitate in the aqueous phase. Further growth of the polymer particles dropped in the water is treated differently.…”

Section: The Mechanism Of Homogeneous Nucleationmentioning

confidence: 99%

“…These models are the "collision process" [123,124], "diffusion process" [27,29], "diffusion/propagational" model (Maxwell et al [125]), "collision/empirical" model (Dougherty [126] and Penlidis et al [127]), "surface coverage" model (Yeliseyeva and Zuikov [128]), and "colloidal" model (Penboss et al [129]). …”

Section: Model Of Styrene Emulsion Polymerization the Effect Of The mentioning

confidence: 99%

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An Advanced Approach on the Study of Emulsion Polymerization: Effect of the Initial Dispersion State of the System on the Reaction Mechanism, Polymerization Rate, and Size Distribution of Polymer-Monomer Particles

Khaddazh¹,

Литвиненко²

2012

Polymerization

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According to these ideas, in the presence of surfactants, the initial emulsion consists of two kinds of particles of different sizes: the monomer droplets with diameters of 5-20 microns and colloidal degree of dispersion and monomer-swollen surfactant micelles (5-10 nm).The mechanism of Harkins-Yurzhenko lied in the base of Smith and Ewart quantitative theory [5][6][7], with further refinements in the works of other authors . The main aspect of this theory is that radicals formed in the aqueous phase are trapped by the monomer swollen surfactant micelles and turn to PMP. It is assumed that only one out of every 100-1000 micelles captures a radical and becomes PMP, and the rest of the micelles are spent to stabilize the growing PMPs. Polymer-monomer particles formation ends with the disappearance of micelles of the emulsifier in the aqueous phase, after which the number of particles remains constant.Initial system contains monomer droplets with a diameter of 5-15 microns, their concentration being 10 12 -10 14 droplets/l, the monomer-swollen micelles with diameters of 5-10 nm and the number of micelles 10 18 -10 21 l -1 , and a water-soluble initiator (usually potassium persulfate) at a concentration of 1% per monomer [8]. Only a small fraction of the molecules of the monomer is located in the interior of the micelles (1-2%) and is dissolved in the aqueous phase (0.03% for styrene). In the aqueous phase, 10 14 -10 16 PMP / l are formed with a diameter in the range of 20-200 nm. Monomer droplets due to their relatively small surface area hardly compete with micelles in capturing radicals.In the polymerization process PMPs increase their size due to the diffusion of the monomer from droplets and monomer-swollen micelles which contains no radicals [1-3, 5, 9-15].Three limiting cases were considered:1. The number of free radicals in the particles is small compared with the total number of radicals, thus the average number of radicals per particle is much less that unity. 2. The average number of radicals per particle is equal to 0.5. This case is realized under following conditions: the activity of the radical in the particle persists as long as the second radical enter the particle, and the time of chain-breaking is small as compared with the average time interval of successive absorption of radicals by the particle. The authors believe that case 2 corresponds to the emulsion polymerization of styrene in the presence of potassium persulfate [5]. The rate of formation of primary radicals is equal to 10 13 radicals• ml -1 s -1 . The average number of polymer particles is of the order of 10 14 -10 16 in 1 ml of the system. If all the radicals formed by the decay of the initiator enter the polymer particles, the average frequency at which a radical enters a particle is once per 10 -100 sec. At any time, the particle contains either one radical or does not contain radicals at all, since it is assumed that chain termination occurs immediately in contact with the second radical in the particle. The particle is inactive unt...

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Section: Aggregative Nucleation Mechanismmentioning

confidence: 99%

Section: The Mechanism Of Homogeneous Nucleationmentioning

confidence: 99%

Section: Model Of Styrene Emulsion Polymerization the Effect Of The mentioning

confidence: 99%

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An Advanced Approach on the Study of Emulsion Polymerization: Effect of the Initial Dispersion State of the System on the Reaction Mechanism, Polymerization Rate, and Size Distribution of Polymer-Monomer Particles

Khaddazh¹,

Литвиненко²

2012

Polymerization

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“…The critical oligomeric radical length would increase with the increasing hydrophilicity of polymer (e.g. ~65 for PMMA, [20], ~5 for PS [21]), thus increasing the solubility of growing chains and delaying the precipitation, further, decreasing the particle number in the nucleation period. Therefore, the initial particle size was largest for PMMA latex particles.…”

Section: Effect Of Reaction Kinetics In Aqueous Phase On Particle Coamentioning

confidence: 99%

A novel approach to prepare large-scale and narrow-dispersed latex particles by emulsion polymerization based on particle coagulation mechanism

Liu

Deng

Sun

et al. 2015

Designed Monomers and Polymers

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In order to understand the mechanism of narrow particle size distribution of the final latex during particle coagulation, a series of experiments were performed to investigate the effect of polymer nature on particle coagulation capability. In particular, thermodynamics and kinetics in aqueous phase were considered to illustrate the detail process of particle coagulation. The final particle size decreased with the increasing side chain length of alkyl methacrylate from 181.5 nm in MMA to 131.6 nm in EMA, 119.3 nm in PMA, and 115.1 nm in BMA, indicating that the particle coagulation capability was proportional to the hydrophilicity of polymer. With increasing polymer hydrophilicity, the affinity between surfactant molecules and particle surface decreased, thus enhancing the particle coagulation capability. Moreover, the critical length of oligomer radical also increased with increasing hydrophilicity and the efficiency of radical capture decreased, thus increasing the saturation of monomer concentration in the inner part of particle, promoting particle coagulation. Combining these results and the La Mer Diagram, a novel approach was developed to prepare large-scale, narrow-dispersed, and high solid content polymer latex based on particle coagulation mechanism. Three criteria, namely, rapid nucleation, fast coagulation, and a long growth period, should be met to produce latex with a narrow particle size distribution.

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“…The best-known alternative theory for particle nucleation is that of "homogeneous nucleation" which includes the formation of particle nuclei in the continuous aqueous phase. This theory is proposed by Priest, Roe and Fitch and Tsai, and extended by Hansen and Ugelstad (HUFT) describes the emulsion polymerization of watersolubble monomers such as vinyl acetate and acrylonitrile, their water solubility though low (< 3%) is much in excess of the amount of monomer which may be solubilized by the emulsifier [43][44][45][46][47][48]. It is also the only mechanism which can apply to monomers of low watersolubility, such as styrene, in emulsifier-free reaction system, and also in reaction system which contain a micellizing emulsifier but at such a concentration that is below the CMC.…”

Section: The Initial Stage (Interval I)mentioning

confidence: 99%

Emulsion Polymerization: Effects of Polymerization Variables on the Properties of Vinyl Acetate Based Emulsion Polymers

Yamak¹

2013

Polymer Science

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Particle Formation in Polymer Colloids, III: Prediction of the Number of Particles by a Homogeneous Nucleation Theory

Cited by 205 publications

References 20 publications

An Advanced Approach on the Study of Emulsion Polymerization: Effect of the Initial Dispersion State of the System on the Reaction Mechanism, Polymerization Rate, and Size Distribution of Polymer-Monomer Particles

An Advanced Approach on the Study of Emulsion Polymerization: Effect of the Initial Dispersion State of the System on the Reaction Mechanism, Polymerization Rate, and Size Distribution of Polymer-Monomer Particles

A novel approach to prepare large-scale and narrow-dispersed latex particles by emulsion polymerization based on particle coagulation mechanism

Emulsion Polymerization: Effects of Polymerization Variables on the Properties of Vinyl Acetate Based Emulsion Polymers

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