Emulsion styrene-butadiene synthesis

Grove s synthesis org chem Production of alkyl chlorides by passing hydrochloric acid into an alcohol In the presence of anhydrous zinc chloride. grovz sin-th3S3s ) GR-S rubber org chem Former designation for general-purpose synthetic rubbers formed by copolymerization of emulsions of styrene and butadiene used in tires and other rubber products previously also known as Buna-S, currently known as SBR (styrene-butadiene rubber). je ar es. rab ar)... 

Styrene-butadiene rubber could be produced by using emulsion and solution process, thus it can be divided into emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). In this entry, we will describe their development and introduce their synthesis process, relationship between structure and property, processing property, blends, and applications. 

Because of their amphiphilic character, alkali resinates have been exploited both as polymer latex stabilizers and as surfactants in emulsion polymerization from the early development of these techniques, as in the pre-Second World War industrial example of the polymerization of 2-chloro-l,3-butadiene, to produce neoprene [68]. In the following decades, other emulsion polymerizations systems, like the synthesis of styrene-butadiene copolymers [68, 69], also called upon these surfactants, which are still being envisaged today, for example, for the polymerization of styrene [70] and chloroprene [71]. However, the reactivity of the conjugated double bond towards free radicals has made it more profitable to use hydrogenated or dehydrogenated rosins rather than their natural forms [68, 72]. 

Method of synthesis MBS consists of an elastomeric core and a glass shell. The elastomeric core is polybutadiene or styrene-butadiene rubber (SBR), and the shell is poly(methyl methacrylate) and polystyrene. The MBS copolymers are synthesized by emulsion polymerization method. In the preparation process PB polymer or SBR have to be synthesized first and then St and MMAare polymerized on rubber particles. Zhou, C Chen, M Tan, Z Y Sun, S L Ao, Y H Zhang. M Y Yang, H D Zhang, H X, Eur. Polym. J., 42, 1811-18,2006. 

The major emulsion processes include the copolymerization of styrene and butadiene to form SBR rubber, polymerization of chloroprene (Fig. t -4) to produce neoprene rubbers, and the synthesis of latex paints and adhesives based mainly on vinyl acetate and acrylic copolymers. The product is either used directly in emulsion form as a paint or else the surfactants used in the polymerization are left in the final, coagulated rubber product. 

The mechanistic principle of the chain transfer exploiting functionalized transfer agents was used for the synthesis of polymer bound CB AO, attached to the polymer chain via the sulfur atom. Weinstein [73, 74] used phenolic and aminic thiols 79, 81 and disulfides 80, 82 as generators of thiyls during free-radical bulk or emulsion copolymerization of butadiene or isoprene with styrene. Systems formed can be considered as bifunctional physically persistent stabiUzers combining CB and HD fiinctions. 

In summary, this pioneering work clearly demonstrated the possibility of aqueous catalytic insertion polymerization of acyclic and cyclic olefins, as well as aqueous ROMP. On the other hand, metal salts without any additional ligands to control the properties of the metal centers were utilized, and activation to the active species was probably also relatively ineffective in most cases. Consequently, catalyst efficiencies were moderate at best. Most of the polymerizations also afforded low molecular weight materials, or employed rather special monomers. The possibility of polymer latex synthesis appears not to have received much attention, although free-radical emulsion polymerization of styrene and butadiene was already a large-scale process at the time. 

Such living conditions are found principally In anlonlcally Initiated systems and Involve common monomers such as styrene, ormethylstyrene, butadiene and Isoprene (1,22). They are far less common In catlonlcally Initiated systems, there being virtually no established example Involving vinyl monomers, but some cyclic monomers such as tetrahydrofuran (THF) and the oxetanes may be polymerized under carefully specified conditions to yield living polymers ( ). Although living free radical systems have also been described In which radicals have been preserved on surfaces. In emulsion, or by precipitation before termination occurs, these are special conditions not easily adapted for clean block copolymer synthesis. 

The possibilities inherent in the anionic copolymerization of butadiene and styrene by means of organolithium initiators, as might have been expected, have led to many new developments. The first of these would naturally be the synthesis of a butadiene-styrene copolymer to match (or improve upon) emulsion-prepared SBR, in view of the superior molecular weight control possible in anionic polymerization. The copolymerization behavior of butadiene (or isoprene) and styrene is shown in Table 2.15 (Ohlinger and Bandermann, 1980 Morton and Huang, 1979 Ells, 1963 Hill et al., 1983 Spirin et al., 1962). As indicated earlier, unlike the free radical type of polymerization, these anionic systems show a marked sensitivity of the reactivity ratios to solvent type (a similar effect is noted for different alkali metal counterions). Thus, in nonpolar solvents, butadiene (or isoprene) is preferentially polymerized initially, to the virtual exclusion of the styrene, while the reverse is true in polar solvents. This has been ascribed (Morton, 1983) to the profound effect of solvation on the structure of the carbon-lithium bond, which becomes much more ionic in such media, as discussed previously. The resulting polymer formed by copolymerization in hydrocarbon media is described as a tapered block copolymer it consists of a block of polybutadiene with little incorporated styrene comonomer followed by a segment with both butadiene and styrene and then a block of polystyrene. The structure is schematically represented below ... 

This paper reports on the synthesis, characterisation, and applications of novel flame retardant dibromostyrene-based latexes. They are copolymers of dibromostyrene with butadiene, alkyl acrylates and methacrylates, vinyl acetate, styrene and unsaturated carboxylic acids, which form a wide variety of flame retardant latexes via an emulsion polymerisation technique. Choice of monomer or monomer blend is based upon the final glass transition temperature of the copolymer desired. Other criteria include desired physical properties and chemical resistance. Dibromostyrene-based butadiene and acryUc latexes are shown to possess the desired physical properties for use in coatings, adhesives and sealants, and the bromine content of the latexes has enabled the material to pass six different flammability requirements for the end uses such as textile backcoating, latex-based paint, contact adhesive, latex sealant, nonwoven binder, and carpet backing. 18 refs. 

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