Emulsification polymerization styrene

Emulsification and Emulsion Polymerization of Styrene Using Mixtures of Cationic Surfactant and Long Chain Fatty Alcohols or Alkanes as Emulsifiers... 

Influence of the Mixed Emulsifier Concentration. The stability of the miniemulsions increases with the concentration of the mixed emulsifier. Table III illustrates these results for the emulsification of two different oils styrene and silicon oil by liposarcosine chlorhydrate with a degree of polymerization of 2. 

Muller and coworkers prepared disc-like polymer Janus particles from assembled films of the triblock copolymer SBM and, after hydrolysis of the ester groups into methacrylic acid units, used these as Pickering stabilizer in the soap-free emulsion polymerization of styrene and butyl acrylate [111]. Armes and coworkers described the synthesis of PMMA/siUca nanocomposite particles in aqueous alcoholic media using silica nanoparticles as stabilizer [112], extending this method to operate in water with a glycerol-modified silica sol [113, 114]. Sacanna showed that methacryloxypropyltrimethoxysilane [115] in the presence of nanosized silica led to spontaneous emulsification in water, which upon a two-step polymerization procedure afforded armored particles with an outer shell of PMMA [116]. Bon and coworkers demonstrated the preparation of armored hybrid polymer latex particles via emulsion polymerization of methyl methacrylate and ethyl methacrylate stabilized by unmodified silica nanoparticles (Ludox TM O) [117]. Performance of an additional conventional seeded emulsion polymerization step provided a straightforward route to more complex multilayered nanocomposite polymer colloids (see Fig. 14). 

Ag-poly(butyl acrylate-co-styrene) nanocomposites were prepared by Yin et al. [410] where the silver nanoparticles were obtained from a microemulsion. An aqueous solution of AgN03 was added to a mixture of toluene, butylacrylate, styrene, sodium dodecyl sulfate and 2-hydroxy-a-methacrylate (HEMA). A transparent microemulsion formed after addition of Span 80 under stirring. This product was bubbled with N2 and irradiated with to y-ray source for 6h (the irradiation helped both polymerization of monomers and reduction of metal ions). Silver particles, collected after de-emulsification by acetone and water, had an average size of about 8.5 nm. 

Microcapsules with a narrow size distribution containing oily core material can be prepared by a Shirazu porous glass (SPG) emulsification technique, followed by a suspension polymerization process. The SPG membrane is a special porous glass membrane with very uniform pore size. Guang Hui Ma et al. have reported the preparation of microcapsules containing hexadecane (oil core) using poly(styrene-... 

N,N-dimethylaminoethyl methacrylate) (DMAEMA) by an SPG emulsification technique [34]. The process consists of two steps - emulsification and polymerization. The oil phase containing monomers (styrene and DMAEMA), hexadecane (HD) and an initiator N.hf-azobis (2,4-dimethyl valeronitrile) (ADVN) is pressed by nitrogen gas through the SPG membrane into the aqueous phase. The aqueous phase contains stabilizer polyvinyl alcohol (PVA), surfactant sodium lauryl sulfate (SLS), electrolyte Na2S04 and water-soluble inhibitor (NaN02 or diaminopheny-lene). The emulsion obtained is then transferred to a separate reaction kettle and polymerization is started by raising the reaction temperature to 70 °G. After 24 h, microcapsules with uniform size are obtained. 

This is in general a heterogeneous free radical polymerization that involves the emulsification of the relatively hydrophobic monomer in water and sometimes an organic phase-in-water emulsifier, followed by the initiation reaction with either a water soluble initiator e.g. sodium persulfate (NaPS)) or an oil-soluble initiator e.g. 2-20-azobisisobutyronitrile (AIBN)) [266]. Typical monomers used in the emulsion polymerization include butadiene, styrene, acrylonitrile, acrylate ester and methacrylate ester, vinyl acetate, and vinyl chloride, but also biopolymers are now obtained by this versatile technique in several mesodimensionate morphologies [267]. 

Here the different steps of the preparation of the nanocomposites are briefly summarized. First, PPO (a low molar mass polymer powder supplied by Sabic-IP, the Netherlands] was end-capped by acetylation in order to avoid inhibition of the styrene polymerization by phenolic OH groups. It was subsequently mixed with styrene and hexadecane. Then the mixture was added to an aqueous solution of 4-dodecylbenzenesulfonic acid (SDBS). This mixture of SDBS/ hexadecane was chosen as a stabilization system since it is suitable to achieve and guarantee efficient stabilization of polymer particles of sizes smaller than 1 ymP The emulsification process was split up into two steps, namely, a first pre-emulsification step performed by ultra-high shear stirring, followed by ultrasonication in order to obtain submicron particles. Finally, the polymerization was initiated and carried out at 80°C under inert atmosphere (final monomer conversion of 90 %]. The latex obtained had a solid content of 23.6 wt% and contained 10 wt% of PPO dissolved in PS and had a particle size of 100 nm. At the end of the polymerization, the PS molar mass was about... 

Azad, A.R.M. etal. (1976) Emulsification and emulsion polymerization of styrene using mixtuiesof cationic surfactant and long chain fatty alcohols or aUcanes as emulsifiers. ACS Symposia Series, 24,1-23. 

Uses Emulsifer for emulsion polymerizafon of vinyl acetate, acrylates, methacrylates, styrene, butadiene, latex for adhesives, paints, paper coatings, textile, and industrial and architectural coaf ngs surfactant for mild light-duty liqs. adhesives, resinous and polymeric coatings for food pkg. defoamer used in the manufacture of food-contact paper and paperboard in components of paper and paperboard in contact with aqueous, fatty, and dry foods Features No VOC or alcohol... 

Uses Wetting agent, solubilizer, emulsifer, dispersant, vise, depressant, mild detergent used in emulsion polymerization of styrene for paints, coatings, textiles, cosmetics, agric. prods. food-pkg. adhesives, paper emulsifer in mfg, of food-cont3ct srticiss... 

Uses Emulsifer, wetting agent, emulsion polymerization of vinyl chloride, styrene, and styrene/acrylic monomers detergent formulations base for shampoos, foaming bath oils, cosmetic emulsions Regulatory FDA compliance... 

Uses Wetting agent, penetrant, emulsifer, dispersant, coemulsifier, surfactant for emulsion polymerization of styrene/butadiene systems Features Hydrophilic rapid wetting Properties Liq. 45% cone. 

Figure 16.6 Micrograph of a polystyrene foam, obtained by polymerization (60 °C, 48 h) in the continuous phase of a water-in-styrene emulsion with 90% aqueous solution, prepared by the spontaneous emulsification method. The scale bar indicates 10 pm. (Adapted from Ref [20], with permission.)...

Figure 7.7 Schematic representation of the process for the preparation of WEPS (a) emulsification of water (blowing agent) in a styrene-PS mixture and (b) suspension polymerization of styrene-PS droplets containing emulsified water. Reproduced from reference 57 by permission of Elsevier.

---