Emulsion soap-free

Precipitation poiymn. Soap-free emulsion poiymn. Seeded poiymn. 

Suspension polymerization may be the most important particle-forming polymerization from an industrial viewpoint. The system is very simple, composed of monomer, initiator, stabilizer, and medium (water in most cases). The monomer droplets with dissolving initiator are dispersed in water and the stabilizer exists at the interface. But suspension polymerization is regarded as a kind of homogeneous polymerization because the polymerization occurs only in monomer droplets and water does not affect the polymerization. Water contributes only to dividing the polymerization locus into small droplets and absorbing the heat evolved by polymerization. On the contrary, in emulsion polymerization, which is another type of polymerization performed in water and as practically important as suspension polymerization, water affects the polymerization significantly. In this section, emulsion polymerization is first discussed, and then some modified emulsion polymerizations such as soap-free emulsion polymerization and micro and mini emulsion polymerizations are described. 

Fig. 11.1.7 Conversions of styrene and acrylamide in soap-free emulsion copolymerization.

Soap-free) emulsion Polymerization lispersion polymerization ... 

Kobayashi et al. [143-146] have synthesized several types of amphiphilic po-ly(2-oxazoline), 34 and its block cooligomers, 53-55, and applied them to soap-free emulsion copolymerization of styrene and vinyl acetate to produce mono-disperse, submicron-sized latex particles. They found that the particle size significantly depended on the type of macromonomer used and generally decreased with increasing the macromonomer concentration. 

Ail microspheres were prepared using soap-free emulsion polymerization. Carboxylated microspheres were prepared by batch copolymerization. Batch copolymerization was performed with main monomer, S, lwt% of co-monomer, MAA, and 0.4wt% of initiator, KPS. All weight fractions were based on the amount of main monomer, S. These microspheres were named CM-1 for low carboxylated PS/PMAA, respectively. 

Polymer microspheres with monodispersed distribution in size are much perferable for phagocytosis assays, because the size dominantly governs phagocytosis of the microspheres by M< ). In addition, the microspheres should be prepared without any surfactants to exclude the influence of the soap molecules adsorbed onto the surface, on phagocytosis of the microspheres. We have synthesized monodispersed polystyrene microspheres by soap-free emulsion polymerization of styrene at 70 °C for 30 hr using potassium persulfate as a initiator [14]. The widely different diameters of the... 

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). 

Yu C-L, Kang J-S, Zhang F-A (2009) The effect of nano-Si02 coUoid on soap-free emulsion polymerization of methyl methacrylate and hydroxyethyl methacrylate. J Macromol Sci A Pure Appl Chem 46(9) 870-875... 

A similar strategy involving Laponite or MMT platelets grafted with polymerizable organotitanate and organosilane molecules was recently reported by Voorn et al. [285, 286]. Here, starved-feed soap-free emulsion polymerization of MMA conducted in the presence of the organoclay led to clay encapsulation. However the solid content was quite low (typically around 7%). 

Fig. 33 Left Synthesis of ciay-armored PMMA latexes through soap-free emulsion polymerization using PDMAEMA-tethered clay as stabiUzen Right TEM image of the so-obtained PMM A/clay composite coUoid. Reproduced from [290] with permission of Wiley Periodicals...

In a quest for different applications various numbers of polymers have been chosen to prepare encapsulated and functionalized magnetic particles by soap-free emulsion polymerization. Examples are amide- and carboxyl-functionalized magnetic latex for protein immobilization [156], and thermally sensitive and carboxyl-functionalized particles for antibody purification [157], bioprocesses... 

Fig. 17 (a) Magnetic latex preparation by soap-free emulsion polymerization, (b) TEM of magnetic polymer particles. Reprinted from [153] with permission... 

KPS as initiator [163]. Liu et al. [164] started with bilayer oleic-acid-coated iron oxide nanoparticles and applied the combination of soap-free and seeded emulsion polymerization (Fig. 20a) to produce GMA-functionalized magnetic poly(MMA-DVB-GMA) microspheres. This was followed by modification of the PGMA shell with EDA to introduce amino groups that can react with the organic dye fiuorescein isothiocyanate and that impart multifunctional, photoluminescence, superparamag-netic and pH-responsive properties to the particles (Fig. 20b). 

Recipe, monomer conversion, particles size and particles number for a series of soap-free emulsion polymerizations of styrene in the presence of macromonomer and increasing concentrations of taponite. 

Mae et al. proposed a micromixer based on repeated splitting and recombination and demonstrated its application for extraction using an emulsion (abbreviated as YM-1) [30]. A soap-free emulsion with a diameter of the order of 1pm can be produced in a short contact time of 0.1 s. The maximum production capacity of a single mixer is 200tyr , which is sufficient for the industrial production of fine chemicals and pharmaceutical compounds. Figure 12.8 shows the results for the extraction of phenol from dodecane into water using the YM-1 and an IMM mixer. 

Mae et al. [18] performed experiments with micromixers with regard to a soap-free emulsion using salad oil and water as the test system. Special attention was also given to the influence of the material of the micromixers on the emulsification process. They found that the proper choice of micromixer material supports the formation of emulsions (Figure 22.9). 

Journal of Applied Polymer Science 82, No.4, 24th Oct. 2001, p.941-7 SOAP-FREE SEEDED EMULSION COPOLYMERIZATION OF MMA ONTO PU-A AND THEIR PROPERTIES... 

Polyurethane acrylate (PU-A) containing a double bond and COOH group was synthesised by the stepwise reaction of TDI, polyetherdiol, dimethylolpropionic acid (DMPA) and 2-hydroxypropyl acrylate (HPA). The PU-A was neutralised with triethylamine and self-emulsified in water to form the PU-A emulsion seed. The seeded emulsion copolymerisation of methyl methacrylate (MMA) onto the PU-A seed was carried out at 80C under soap-free conditions and an anionic latex of P(UA-MMA) was obtained. The structure of the P(UA-MMA) copolymer, its latex properties and the cast film were significantly affected by the amounts of HPA, DMPA and MMA. The results were discussed. 21 refs. 

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