Monodispersed micron-size particles

In such a two-stage process, monodisperse micron-sized particles were produced and a rather good correlation between... 

Thus the use amphiphilic macromonomers is another method to achieve the particle formation and their subsequent stabilization. Macromonomers can be pre-reacted to form graft copolymers, which are be introduced into the reaction medium afterwards. Macromonomers can also be copolymerized with classical monomers in situ to form graft copolymers. This is a simple and flexible method for producing monodisperse micron-sized polymer particles. Macromonomers can produce ion-free acrylic lattices with superior stability and film forming properties compared to conventional charge stabilized lattices. These non-con-... 

DeSimone and his co-workers have intensively studied polymerization reactions in an environmentally friendly solvent, C02. In the presence of C02-philic silicone-based macromonomer, 45, relatively monodisperse micron-sized polymer particles were obtained by the polymerization of MMA and styrene in supercritical C02 [123]. 

There are few methods suitable for on-line chemical analysis of aerosol particles. Raman spectroscopy offers the possibility of identifying the chemical species in aerosol particles because the spectrum is specific to the molecular. structure of the material, especially to the vibrational and rotational modes of the molecules. Raman spectra have been obtained for individual micron-sized particles placed on surfaces, levitated optically or by an eiectrodynamic balance, or by monodisperse aerosols suspended in a flowing gas. A few measurements have also been made for chemically mixed and poly disperse aerosols. The Raman spectrum of a spherical particle differs from that of the bulk material because of morphology-dependent resonances that re.su It when the Raman scattered photons undergo Mie scattering in the particle. Methods have been developed for calculating the modified spectra (McNulty el al., 1980). 

Coating PANI onto various matrixes has been studied for a long time [38,39]. In particular, monodispersed particles with a perfect spherical shape are generally preferred as model ER materials to investigate ER effect since the morphology of the dispersed phase is one of the critical parameters. However, PANI particles synthesized by conventional oxidization polymerization are often of irregular shape. Therefore, to obtain monodispersed PANI ER particles, researchers have used monodispersed polymer spheres as core to develop various PANI-coated ER particles. For example, Jun et al. [40,41] have used monodisperse micron-sized porous... 

J.B. Jun, J.W. Kim, K.D. Suh, Monodisperse micron-sized polyaniline composite particles for electrorheological fluid material, Macromol. Chem. Phys., 2002, 203,1011. 

Recent research build upon this idea of size separation and showed that monodisperse micron-sized partides sediment as dose as possible toward the periphery the actual distance between the location of segregated partides and the contad line increases with increasing partide size. This preferential deposition of partides is caused by the wedge-shaped dome of the drying droplet, which physically limits the ability of the larger particles to move nearer to the periphery, as schematically depiaed in Figure 22. 

The sacrificial core approach entails depositing a coating on the surface of particles by either the controlled surface precipitation of inorganic molecular precursors from solution or by direct surface reactions [2,3,5,6,8,9,33-35,38], followed by removal of the core by thermal or chemical means. Using this approach, micron-size hollow capsules of yttrium compounds [2], silica spheres [38], and monodisperse hollow silica nanoparticles [3,35] have been generated. 

Colloidosomes are a recent class of microcapsules and thus far have only been applied to catalysis and drug delivery in a few cases. The term colloidosomes was coined by Anthony Dinsmore and colleagues in 2002 to refer to capsules where the shells are composed of close-packed layers of monodisperse colloidal particles (usually micron-sized polymer beads) that have been linked together by sintering. 

Micron-size — Monodisperse spherlite E submicron particle... 

Dispersion copolymerization of PEO-MA macromonomers (Cj-fEO -MA, C1-(EO)48-C6-MA, C1-(EO)48-C10-MA) with MMA was successful in producing very stable PMMA dispersions of micron size [81]. In this case, however, Cr (EO)48-MA was more effective in giving monodisperse particles than C1-(EO)48-C10-MA (the reverse is true with styrene, see above). The particles obtained were found to have uneven surfaces with a number of craters. These results suggest that some compatibility between PMMA and PEO chains and also between PMMA and the medium (methanol/water) may play a role in controlling the particle formation. 

Micron-size monodisperse polymeric microspheres are used in a wide variety of applications, such as toners, instrument calibration standards, column packing materials for chromatography, spacers for liquid crystal displays, and biomedical and biochemical analysis [1-3]. Because of the commercial and scientific interest in these particles, research into their preparation has been active... 

Core-shell polystyrene-polyimide high performance particles have been successfully prepared by the dispersion copolymerization of styrene with vinyl-benzyltrimethyl ammonium chloride (VBAC) in an ethanol-water medium using an aromatic poly(amic acid) as stabilizer, followed by imidization with acetic anhydride [63]. Micron-sized monodisperse polystyrene spheres impregnated with polyimide prepolymer have also been prepared by the conventional dispersion polymerization of styrene in a mixed solvent of isopropanol/2-methoxyethanol in the presence of L-ascorbic acid as an antioxidant [64]. 

Two-step swelling polymerization starts with the preparation of sub-micron sized non cross-linked seed particles by emulsion polymerization. The seed particles are then added to a pre-polymerization mixture. The particles swell in the mixture and the polymerization takes place within the volume of the swollen particles [91]. The procedure, which results in monodisperse particles, has been used for the preparation of MIPs imprinted with a range of templates [92-97]. 

Okubo, M., Shiozaki, M., Tsujihiro, M., and Tsukuda, Y., Preparation of micron-size monodisperse polymer particles by seeded polymerization utilizing the dynamic swelling method. Colloid Polym. Sci., 269, 222-226 (1991). 

Temperature-sensitive micron-sized monodispersed composite polymer particles were prepared by seeded copolymerisation of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate with 1.77 micrometresized monodispersed PS seed particles. The change in surface properties at temperatures above and below 35C was examined by DSC, trypsin activity and the adsorption/ desorption behaviours of low molecular weight cationic emulsifier as well as biomolecules. From the results, it is concluded that the micron sized monodispersed PS/ poly(dimethylaminoethyl methacrylate-co-ethylene glycol dimethacrylate) composite particles can be expected to be a temperature-sensitive carrier for biomolecules. Potential in chromatographic applications is suggested. 20 refs. 

Okubo et al. examined the penetration/release behavior of various solvents in-to/from the interior of micron-sized monodisperse cross-linked polystyrene/poly-divinylbenzene composite particles [63]. The hollow particles were produced by the seeded polymerization utilizing the dynamic swelling method [64], Itou et al. prepared crosslinked hollow polymer particles of submicron size by means of a seeded emulsion polymerization [65]. The morphology of the particles depends on the composition of divinylbenzene and methyl methacrylate. 

Okubo M, Takekoh R, Suzuki A (2002) Preparation of Micron-sized, Monodisperse Poly(methyl methacrylate)/Polystyrene Composite Particles Having a Large Number of Dents on Their Surfaces by Seeded Dispersion Pol3meiization in the Presence of Decalin. Colloid Pol3un. Sci. 280 1057-1061. 

Lee KC, Wi HA. Highly crosslinked micron-sized, monodispersed polystyrene particles by batch dispersion polymerization. Part 1 Batch, delayed addition, and seeded batch processes. J Appl Polym Sci 2010 115 297-307. 

One of the fascinating application of macromonomers is in the field of dispersion polymerization. The dispersion polymerization in the presence of suitable stabilizers affords mostly monodisperse submicron- and micron-sized microspheres (particles). The macromonomers are graft-copolymerizaed during copolymerization in the continuous phase and so accumulate on the particle surface, so that the resulting particles are effectively sterically stabilized against flocculation. Amphiphilic copolymers s mthesized by copolymerization of a hydrophobic conventional monomer with a hydrophilic macromonomer and vice verse present all the typical properties of conventional surfactants. They aggregate between themselves and form a micelle in the aqueous or non-aqueous media. The conformation of a micelle formed by PEO-g-PSt polymer in the aqueous medium consists of a hydrophobic PSt core and a hydrophilic PEO shell (Fig. 10). 

A styryl-type macromonomer having a water-soluble ROZO segment (Scheme 47) or having an amphiphilic ROZO block copolymer (Scheme 51) was extensively used as surfactant for the emulsion or dispersion polymerization. Polymerization of St or MMA in the presence the macromonomer as stabilizer (less than 3 wt% for the total monomer) in water took place with a radical initiator to give stable monodisperse polymer particles with a micron-size diameter. The macromonomer acted as both comonomer and stabilizer actually the copolymerization occurred. Therefore, the system is micelle forming but soap-free. Hydrophilic PMeOZO segments are preferential on the particle surface. 

Tokuda M, Minami H, Mizuta Y, Yamagami T (2012) Preparation of micron-sized monodisperse poly(ionic liquid) particles. Macromol Rapid Commun 33 1130-1134... 

Stober W, Fink A, Bohn E Controlled growth of monodisperse silica particles in the micron size range, J Colloid Interface Sd 26 62-69, 1968. 

Okubo, M., Minami, H., and Morikawa, K. (2003). Influence of shell strength on shape transformation of micron-sized, monodisperse, hollow polymer particles. 

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