Polymerizable surfactants emulsion polymerization using

In the domain of polymer stabilization (polymerization in dispersed media as well as using physico chemical procedures), it becomes of first importance to anchor the surfactant onto the surface of the particles not only to avoid flocculation, but also to limit water pollution. In the case of emulsion polymerization, a good way to overcome these drawbacks is to use polymerizable surfactants (also called "surfmers") [4-6]. 

Uses Polymerizable surfactant for vinylic systems antistatic props. promotes adhesion of pigments used for emulsion polymerization in paper, textile, fiber, and adhesives... 

In recent years, there has been a considerable interest in the use of polymerizable surfactants for latices. Such surfactants contain a polymerizable group which may be an acrylate, a methacrylate, an allyl ether or a maleate double bond. Both anionic and nonionic reactive surfactants are commercially available. The polymerizable surfactant is usually added from the beginning, in essence serving as a comonomer in the emulsion polymerization. The reactive surfactant may... 

Microgels which have been prepared in emulsions or microemulsion have a more compact structure than those obtained by polymerization in solution. For microemulsion copolymerization, preferentially self-emulsifying comonomers, such as unsaturated polyesters, are used as polymerizable surfactants, because no emulsifier must be removed after the reaction. By choosing suitable monomer combinations the composition, size and structure of microgels can be widely varied, thus adjusting these macromolecules to special applications. 

Polymerizable surfactants capable of working as transfer agents include thiosulfonates, thioalkoxylates and methyl methacrylate dimer/trimer surfactants. Thioalkoxylates with 17-90 ethylene oxide units were produced from ethoxylated 11 bromo-undecanol by replacing the bromine with a thiol group via the thiazonium salt route [8]. In the presence of water-soluble azo initiator the thio ended Transurfs (used at a concentration above the CMC) gave monodispersed latex particles in emulsion polymerization of styrene. However, the incorporation of the Transurf remained low, irrespective of the process used for the polymerization (batch, semibatch, seeded). The stability of the lattices when the surfactant and the transfer function were incorporated in the same molecule was better than when they were decoupled. 

Cochin D, Laschewsky A, Nallet F. Emulsion polymerization of styrene using conventional, polymerizable, and polymeric surfactants. A comparative study. Macromolecules 1997 30 2278-2287. 

Emulsion polymerization is used in the chemical industry to produce a milky fluid called latex which is used as the synthetic rubber raw material in paints, surface coatings, adhesives, paper, textile and leather treatment chemicals and in the manufacture of various other products. In-situ formed micelles are used in order to perform an emulsion polymerization process, carried out in an aqueous medium. There are four basic ingredients required for emulsion polymerization. They are (a) the monomer, a polymerizable organic material, (b) the water dispersion medium, (c) the emulsifier (surfactant) and (d) the initiator. When correct amounts of the ingredients are mixed together properly in a suitable... 

Concerning colloidal applications, the uses as dispersants or emulsifiers are the most frequent ones. But although there exist several studies on the use of polymerizable surfactants [82,91,93,219,251,314,333,337,352,452-477] - i.e. of the precursors for polysoaps - the use of polysoaps in emulsion polymerization is still the exception [376]. In both cases improved latex stabilities and improved resistance to moisture of film-formed latexes were aspired to, but at least in the former case the results were often disappointing [93, 251, 470-472]. Polysoaps are used to stabilize lattices [214, 230], The opposite use for flocculation has also been tested, [284], Polysoaps have also been studied as viscoelastic fluids [108]. 

Another strategy consists in the use of QDs coated with a cysteine acrylamide, a polymerizable stabilizer [304]. Successful incorporation of hydrophilic cysteine-acrylamide-stabilized QDs into 80-200 nm fluorescent latexes was achieved via emulsion polymerization, as reported by Sherman et al. [308], using two different procedures. In the first, a two-step shot growth surfactant-free emulsion polymerization of styrene and NaSS was performed in the presence of a solution of hydrophilic cysteine-acrylamide-stabilized CdS or CdSe/CdS QDs. In the second approach, CdSe/CdS QDs were first electrostatically modified by vinylbenzyl(trimethyl)-ammonium chloride and subsequently copolymerized with styrene in the presence of SDS. A third approach was also described in this paper coating of cationic PS particles with anionic poly(cysteine acrylamide)-coated QDs through electrostatic-driven interactions. 

In liquid-liquid two-phase systems, the solubility characteristics of the initiator are important. The distribution of initiator between oil and water phases should be such that it is predominantly present in the phase where the polymerizable function is located. The polymerization depicted in Figure 17.24 is best served with a water-soluble initiator, whereas that of Figure 17.25 proceeds best with an oil-soluble one. In the most important application of polymerizable surfactants, that of emulsion polymerization (see below), water soluble initiators, such as potassium persulfate and hydrophilic azo compounds, are used. 

Polymerizable surfactants are of interest in emulsion polymerization, e.g. in the conversion of vinyl chloride to poly(vinyl chloride) (PVC) and of acrylates and vinyl acetate to lattices for coatings. Use of a reactive surfactant in vinyl chloride polymerization leads to PVC with improved shear stability. In lattices, polymerizable surfactants can bring about several advantages such as the following ... 

The second major use of polymerizable surfactants is their application as stabilizer in polymerization in dispersed media, chiefly in emulsion polymerization, but also in dispersion polymerization. 

ABS) and polyvinyl chloride (PVC). In the emulsion polymerization, reactive surfactants can be used as inisurfs when they can replace both the initiator and the surfactants, as transurfs when they may be used to control the molecular weight, and finally as surfmers when they are used as comonomers which are polymerizable. 

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