Polystyrene-beads

Combinatorial chemistry has significantly increased the nurnjjers of molecules that can be synthesised in a modern chemical laboratory. The classic approach to combinatorial synthesis involves the use of a solid support (e.g. polystyrene beads) together with a scheme called split-mix. Solid-phase chemistry is particularly appealing because it permits excess reagent to be used, so ensuring that the reaction proceeds to completion. The excess... 

Other Plastics Uses. The plasticizer range alcohols have a number of other uses in plastics hexanol and 2-ethylhexanol are used as part of the catalyst system in the polymerization of acrylates, ethylene, and propylene (55) the peroxydicarbonate of 2-ethylhexanol is utilized as a polymerization initiator for vinyl chloride various trialkyl phosphites find usage as heat and light stabHizers for plastics organotin derivatives are used as heat stabHizers for PVC octanol improves the compatibHity of calcium carbonate filler in various plastics 2-ethylhexanol is used to make expanded polystyrene beads (56) and acrylate esters serve as pressure sensitive adhesives. 

Economics. Rigid foam systems are typically in the range of 32 kg/m (2 Ibs/fT) and, in 1992, had a foam price of about 3.63/kg ( 1.65 per lb) with hquid foam systems at about 2.75/kg. Unit prices for pour-ia-place polyurethane packaging systems fall between the competitive expandable polystyrene bead foam at 3.30/kg and low density polyethylene foams at 5.80/kg. 

Expanded polystyrene bead mol ding products account for the largest portion of the drinking cup market and are used in fabricating a variety of other products including packaging materials, iasulation board, and ice chests. The iasulation value, the moisture resistance, and physical properties are inferior to extmded boardstock, but the material cost is much less. 

C Q—C g-ethoxylated quaternaries surfactants for coating polystyrene beads in the manufacture of lightweight concrete 17... 

The monomer 4-styrenesulfonic acid was prepared by dehydrohalogenation of -bromoethjibenzene—sulfonyl chloride. The potassium salt can be polymerized in aqueous solution (222). The sulfonation of cross-linked polystyrene beads is being carried out in industry with concentrated sulfuric acid. 

Polymer—Cp—MCl complexes have been formed with the Cp-group covalendy bound to a polystyrene bead. The metal complex is uniformly distributed throughout the bead, as shown by electron microprobe x-ray fluorescence. Olefin hydrogenation catalysts were then prepared by reduction with butyl hthium (262). 

Rhodacarborane catalysts have been immobilized by attachment to polystyrene beads with appreciable retention of catalytic activity (227). A 13-vertex /oj iJ-hydridorhodacarborane has also been synthesized and demonstrated to possess catalytic activity similar to that of the icosahedral species (228). Ak-oxidation of closo- >(2- P((Z [) 2 - i- > l[l-Bih(Z, results in a brilliant purple dimer. This compound contains two formal Rh " centers linked by a sigma bond and a pak of Rh—H—B bridge bonds. A number of similar dimer complexes have been characterized and the mechanism of dimer formation in these rhodacarborane clusters have been studied in detail (229). 

Roofiag panels have been made from polyisocyanurate foams, both foam- and felt-reiaforced with glass fiber. PhenoHc resias are used especially for decorative laminates for paneling. The substrate may be fiberboard or a core of expanded polystyrene beads. In one case the beads are coated with phenoHc resia, then expanded ia a mold to form a stmctural foam panel. 

POLYSTYRENE BEADS, EXPANDED, MIXTURE UITH FLAMMABLE LIQUID 2211 ... 

The pore size, the pore-size distribution, and the surface area of organic polymeric supports can be controlled easily during production by precipitation processes that take place during the conversion of liquid microdroplets to solid microbeads. For example, polystyrene beads produced without cross-linked agents or diluent are nonporous or contain very small pores. However, by using bigb divinylbenzene (DVB) concentrations and monomer diluents, polymer beads with wide porosities and pore sizes can be produced, depending on the proportion of DVB and monomer diluent. Control of porosity by means of monomer diluent has been extensively studied for polystyrene (3-6) and polymethacrylate (7-10). 

High-performance size exclusion chromatography is used for the characterization of copolymers, as well as for biopolymers (3). The packings for analyses of water-soluble polymers mainly consist of 5- to 10-/Am particles derived from deactivated silica or hydrophilic polymeric supports. For the investigation of organosoluble polymers, cross-linked polystyrene beads are still the column packing of choice. 

Movements of single myosin molecules along an actin filament can be measured by means of an optical trap consisting of laser beams focused on polystyrene beads attached to die ends of actin molecules. (Adapted from Finer et at., 1994. Nature 368 113- 119. See also Block, 1995. Nature 378 132 133.)... 

Figure 12-5. The Lummus Crest Inc. process for producing polystyrene " (1) reactor, (2) holding tank (Polystyrene beads and water), (3) centrifuge, (4) pneumatic drier, (5) conditioning tank, (6) screening of beads, (7,8) lubrication and blending, (9) shipping product.

Fill the existing wall cavity with a suitable insulant such as fiberglass, rock wool, polystyrene beads or foam. The greater the thickness of the cavity, the lower the CZ-value. 

Amos prepared his polymer-supported reagent in two steps from commercially available polystyrene beads (bromination, then condensation with lithium diphenylphosphide). He found that a useful range of sulphoxides could be reduced effectively, in good yields and in a few hours, to give clean samples of sulphides. 

Grafting of 2-methyloxazoline onto chloromethylated polystyrene beads in benzonitrile at 110 °C gave graft copolymers, which were hydrolyzed to poly(styrene-g-ethylenimine) and useful as a chelating resin370. ... 

The approximately round shape and small size of the suspension beads is useful for some applications such as expandable polystyrene or as an intermediate for further compounding with pigments, other polystyrene beads, etc. Being round, however, they tend to roll, not only causing a safety hazard when spilled on floors but more importantly causing difficulties in some fabricating extruders and molding machines. Except for expandable polystyrene, beads are seldom sold as such but are extruded into pellets. 

Suspension Polymerization. Water is the suspending phase. Inorganic salts and vigorous agitation prevent coalescence and agglomeration. The reaction mode is batch. The largest use of suspension polymerization is for the manufacture of expandable polystyrene beads. 

The immobilization of metal catalysts onto sohd supports has become an important research area, as catalyst recovery, recycling as well as product separation is easier under heterogeneous conditions. In this respect, the iron complex of the Schiff base HPPn 15 (HPPn = iVA -bis(o-hydroxyacetophenone) propylene diamine) was supported onto cross-linked chloromethylated polystyrene beads. Interestingly, the supported catalyst showed higher catalytic activity than the free metal complex (Scheme 8) [50, 51]. In terms of chemical stability, particularly with... 

Scientists also have learned how to mimic the surface of a butterfly wing. Polystyrene beads and smaller silica nanoparticles are suspended in water and mixed thoroughly using ultrasound. When a glass slide is dipped into the suspension and slowly withdrawn, a thin film forms on the glass surface. This film is a regular array of beads encased in a matrix of nanoparticles. Heating the film destroys the polystyrene beads but leaves the silica web intact. The result is a silica inverse opal film. 

Figure 34 A polymer-supported metallocene catalyst (51) with a weakly coordinating anion, [B(C6F5)4] , produced from lightly cross-linked, chloromethylated polystyrene beads for olefin polymerization. (Adapted from ref. 75.)...

Iron flake powder and polystyrene beads had been blended in a high-speed mixer. The mixture ignited and binned rapidly when discharged into a polythene bag. Rapid oxidation of the finely divided metal and/or static discharge may have initiated the fire. No ignition occurred when the iron powder was surface coated with stearic acid. 

---