A comprehensive experimental study of surfactant-free emulsion polymerization of styrene

Tauer, Klaus; Deckwer, R.; Kühn, I.; Schellenberg, C.

doi:10.1007/s003960050433

Cited by 101 publications

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“…A further development of the mechanism of nucleation of aggregate particles is reflected in the publications of Tauer, Kuhn et al [52][53][54][55][56][57]66]. 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: 97%

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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: 97%

“…Later on, these ideas found their development in the investigations of Priest [35], Roe [36], Fitch and Tsai [39,40], Yeliseyeva [37,38], Christiansen [44], Ugelstad [27], Pepard [45] Wilkinson [46][47][48], Oganesyan [49][50][51], Tauer [52][53][54][55][56][57], etc.…”

Section: The Mechanism Of Homogeneous Nucleationmentioning

confidence: 99%

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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“…Several literature had been reported about surfactant free emulsion polymerization, in this section a brief hint about these publications will be considered. Tauer et al [45] studied the surfactant-free emulsion polymerization of styrene initiated by KPS. Wang and Pan [46] studied the surfactant-free emulsion polymerization of styrene with the water soluble co-monomer as 4-vinylpyridine.…”

Section: Surfactant Free Emulsion Polymerizationmentioning

confidence: 99%

Emulsion Polymerization Mechanism

El-hoshoudy¹

2018

Recent Research in Polymerization

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Emulsion polymerization is a polymerization process with diferent applications on the industrial and academic scale. It involves application of emulsiier to emulsify hydrophobic polymers through aqueous phase by amphipathic emulsiier, then generation of free radicals with either a water or oil soluble initiators. It characterized by reduction of bimolecular termination of free radicals due to segregation of free radicals among the discrete monomer-swollen polymer particles. The latex particles size ranged from 10 nm to 1000 nm in a diameter and are generally spherical. A typical of particle consist of 1-10,000 macromolecules, where macromolecule contains about 100-10 6 monomer units.Keywords: emulsion polymerization, emulsiied monomers, particle nucleation and polymerization mechanism IntroductionEmulsion polymerization is a unique process involves emulsiication of hydrophobic monomers by oil-in water emulsiier, then reaction initiation with either a water soluble initiator (e.g. potassium persulfate (K 2 S 2 O 8 ) or an oil-soluble initiator (e.g. 2,2-azobisisobutyronitrile (AIBN)) [1,2] in the presence of stabilizer which may be ionic, nonionic or protective colloid to disperse hydrophobic monomer through aqueous solution [3,4]. Typical polymerization monomers involve vinyl monomers of the structure (CH 2 =CH-). These emulsion polymers ind a wide range of applications such as synthetic rubbers, thermoplastics, coatings, adhesives, binders, rheological modiiers, plastic pigments [1]. Emulsion polymerization is a rather complex process because nucleation, growth and stabilization of polymer particles are controlled by the free radical polymerization mechanisms in combination with various colloidal phenomena [1]. Aside from other polymerization techniques, emulsion polymerization afords increasing molecular weight of the formed latexes through decreasing polymerization rate by either decreasing initiator concentration or lowering reaction temperature [5,6].© 2018 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Systems of emulsion polymerization involve (1) conventional emulsion polymerization, in which a hydrophobic monomer emulsiied in water and polymerization initiated with a watersoluble initiator [5]. (2) Inverse emulsion polymerization [7], where organic solvents of very low polarity as parain or xylene used as a polymerization media to emulsify hydrophilic monomers [5], then initiation proceed with the aid of hydrophobic initiator [5]. These two polymerization types known as oil-in-water (o/w) and water-in-oil (w/o) emulsions [5]. (3) Mini emulsion polymerization involves systems with monomer droplets in water with much smaller droplets than in emulsion polymerization and characterized by monomer droplet =50-1000 nm, surfactant concentration < critical micelle co...

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“…It is worthwhile to note that we carefully selected VA-086 as the initiator. VA-086 is a watersoluble nonionic initiator and no success has been reported in surfactant-free emulsion polymerization of styrene (Tauer et al, 1999). In order to verify the sole stabilizing effect of silica nanoparticles, emulsifier-free emulsion polymerization using VA-086 as the initiator in the absence of nanoparticles was performed.…”

Section: Characterization Of the Polystyrene-silica Core-shell Composmentioning

confidence: 99%

Advanced Core-Shell Composite Nanoparticles Through Pickering Emulsion Polymerization

Dai¹

2012

The Delivery of Nanoparticles

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A comprehensive experimental study of surfactant-free emulsion polymerization of styrene

Cited by 101 publications

References 1 publication

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

Emulsion Polymerization Mechanism

Advanced Core-Shell Composite Nanoparticles Through Pickering Emulsion Polymerization

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