Surface modified polystyrene particle

Surface-modified Polystyrene Particles as Model Carriers... 

Surface modified polystyrene particles as model carriers... 

The hydrophobic macroporous polystyrene beads are exceptionally chemically stable and are used for organic phase gel permeation chromatography products, Styragel (Waters) and PLgel (Polymer Laboratories) and reversed phase HPLC separations, PRP (Hamilton) and PLRP-S (Polymer Laboratories). It is possible to surface modify the particle to mask the hydrophobicity of the base polymer and produce ion exchange and hydrophilic materials, PI SAX, PL-GFC (Polymer Laboratories). In the microporous form after derivatisation to form strong cation exchangers these materials are commonly used for carbohydrate and amino acid separations, Aminex (BioRad). 

Kobayashi et al. [91] recently synthesized a phase that is comprised of thiol-modified gold-coated polystyrene particles. An increase in the selectivity of the anthracene-phenanthrene pair was observed on the Cis-Au particle when compared with a traditional monomeric Cis phase with a surface coverage of 3.0 p,mol/m. This isomer pair is not the ideal choice for the determination of shape selectivity however, this synthetic technique should in general lead to dense, ordered phases that are anticipated to yield relatively highly shape-selective chromatographic separations. 

To simulate the toner-silica interactions, PS/PMMA blends were used as a model for polystyrene/acrylic toners. Silicon tips modified either with HMDS or with PDMS were applied to model surface-treated silica particles. The Pulsed Force Mode images of PS/PMMA films displayed... 

The application of thermal FFF to a variety of colloids and particles has been demonstrated in both aqueous and organic carrier liquids. Figure 2 illustrates the dependence of retention on the surface composition of polystyrene particles. The three particles are similar in size, but the surface of one of the samples has been carboxylated, whereas another has been am-inated. The relative elution order of the three particles can be changed by modifying the carrier liquid [13]. 

Zeolite shells on polystyrene beads were prepared by a combination of layer-by-layer (LbL) and hydrothermal synthesis techniques. The negatively charged polystyrene beads were surface modified in order to adsorb zeolite Beta nanocrystals. Such particles were then adsorbed on the surface of the beads and induced to grow into a continuous film of intergrown crystals of zeolite Beta. The effect of the preliminary treatment on the formation of the zeolite film was studied. Finally the polystyrene beads used as macro-templates were removed by calcination in air, yielding hollow spheres of zeolite Beta. The zeolite Beta/polystyrene composites and the corresponding hollow zeolite spheres were characterized by XRD, SEM, TG/DTA and BET surface area measurements. 

Titania nanoparticles were first surface-modified with polybutylene succinimide diethyl triamine (OLOA370) [87-91] and then 5wt% of the hydrophobized material was dispersed in styrene prior to a miniemulsification process. About 89% of the titania could be encapsulated in 73% of the PS, but pure polystyrene particles were still detected. Another efficient compatibilizer for titania is Solsperse 32000, a polyamine/polyester. By modifying titania with this polymer, hybrid nanoparticles with PS and PS-co-polybutylacrylate(PS-co-PBA) could be generated [92-95]. 

Due to the relatively weak adsorption of homopolymers at the L/L interface, and in some cases at the S/L interface, homopolymers are seldom used as emulsifiers or dispersants. For this purpose, the molecule is modified to include some specific units that have strong adsorption to the surface. A good example is partially hydrolysed poly (vinyl acetate), which is commercially referred to as poly(vinyl alcohol) (PVA). The polymer contains 4-12% acetate groups (i.e. 96-88% hydrolysed) and these groups impart an amphipathic character to the chain. The polymer becomes surface-active at the L/L interface and hence it can be used as an emulsifier. In addition, on a hydrophobic surface such as polystyrene, the acetate groups become preferentially adsorbed on the surface of the particles, thus leaving the PVA units dangling in solution as loops and tails . The latter provide the required steric stabilization. 

Lao.9oCeo.ioP04 nanocrystals were surface modified with mixed surfactants a mixture of DDA and BEHP or a mixture of OA and BEHP. The surface modified nanocrystals were dispersed at SO wt % in polystyrene, forming translucent thick films on quartz discs. Pulse height spectra from alpha particle detection (Source Am) of nanocrystal samples superimposed with the result from a highly efficient plastic scintillator, BC-400 are presented in Figure 3. 

Hong et al. [Ill] modified ZnO nanoparticles by grafting polystyrene (PS) onto the surface of particles. This procedure contained two steps first, the surface of ZnO nanoparticles was activated by KH570, and second, PS was grafted to the surface-activated ZnO nanoparticles through typical solution polymerization. Hong et al. [112] also investigated the radical polymerization of methyl methacrylate (MMA) on the surface of ZnO particles to which the functional double bond had first been introduced. 

Figure4.28 Daisy-shaped and multipod-like silica/polystyrene particles produced by emulsion polymerization. The silica particles have been surface-modified by a moderate amount of the MPS silane coupling agent...

As presented in the introduction, the nature of the substrate used for the above-described electrostatic layer-by-layer deposition is not cmcial, as long as it is charged. For example, PAH/PSS multilayers have been prepared on plasma-treated glass [85,86], as cleaved mica [87], silicon functionalized by 3-aminopro-pyldimethoxysilane [88], surface-oxidized poly(4-methyl-l-pentene) [89], chemically modified poly(chlorotrifluoroethylene) (PCTFE) [90,91], plasma-modified poly(tetrafiuoroethylene) (FIFE) [92,93], chemically modified as well as untreated poly(ethylene terephtalate) (PET) [94], gold surfaces modified with mer-captopropionic acid [76], and many others. PAH/PSS multilayers have also been grown on chemically modified polystyrene [95] and melamine formaldehyde latex particles [96,97]. Multilayer assembly on latex particles was either accomplished by adsorption from solutions of high polyelectrolyte concentration with... 

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