Polymeric materials polystyrene beads

POLYMERIC BEADS, EXPANDABLE (POLYSTYRENE or POLYSTYRENE BEADS, EXPANDABLE) (9003-53-6) (CgHg), (flash point 644 to 662°F/340 to 350°C autoignition temp 801°F/427°Cf "l). Incompatible with strong oxidizers, hydrocarbon solvents. Decomposes above 572°F/300°C, producing toxic styrene, benzene, carbon monoxide, and other hydrocarbon fumes. On small fires, use alcohol-resistant foam, dry chemical powder, water spray, or CO extinguishers. Note This material may be shipped in a flammable solvent. Check MSDS and refer to solvent carrier. 

Polystyrene resin, frequently used resin material for solid-phase peptide synthesis (SPPS). The polymeric support for SPPS must be chemically inert, mechanically stable, completely insoluble in the solvents used, and easily separated by filtration. For many applications a copolymer of polystyrene with 1% of divinyl benzene as crosslinker is used. The dry resin beads are able to swell up to the five-or sixfold volume in the different organic solvents mainly used for peptide synthesis (e.g., dichloromethane or dimethylfor-mamide). For SPPS the resin material must be chemically functionalized in order to allow for attachment of a handle/liker (e.g. Wang resin), or the first amino acid (—> Merrifield resin). Hydrophilic tentacle polymers gels (TentaGel) are obtained by grafting polyethylene glycol (PEG) chains with an arbitrary degree of polymerization onto porous polystyrene beads. 

In the first mode, known portions of the polymer were equilibrated with solutions of CaCl2 and HCl, as well as with their mixtures of known concentrations. The final composition of the bulk solutions in equilibrium with the polymeric phase was determined by titrating the excess HCl acid with NaOH and hy complexometric titration of the Ca ions with ethylenediamine tetraacetate (EDTA). From these data the concentrations of the electrolytes within the porous space of the polymeric material were calculated and then the apparent phase distribution coefficients k of HCl and CaCl2, defined as the ratio between the equihbrium concentrations of the corresponding electrolytes within and outside the polymeric beads. These calculations are strongly facifitated by the outstanding property of the neutral hypercrossfinked polystyrene sorbents, namely that their swelling does not depend on the electrolyte concentration, so that the volume of the porous space remains constant in all experiments. Thus,... 

Polymeric Beads, Expandable Polystyrene Beads, Expandable Plastics Moulding Compound A moulding material in bead or granular form consisting predominantly of polystyrene, poly(methyl methacrylate) or other polymeric material and containing 5% to 8% of a volatile hydrocarbon which is predominantly pentane. During storage a small proportion of this pentane is released to the atmosphere this proportion increases at elevated temperatures. IMO 9036... 

Because these crosslinked polystyrene beads have pore sizes that are controlled by suspension polymerization parameters and the crosslinking density of the polymer, they are being used as column packing materials for size-exclusion chromatography, also known as gel permeation chromatography (GPC). The crosslink density increases with increased divinyl benzene concentration. 

Many different support materials were developed [3, 4] since the original use by Merrifield of a polystyrene-based support material for polypeptide synthesis [5]. The work of Merrifield is described in Chap. 8 (see section on proteins). Beads of copolymers of styrene with divinyl benzene are available commercially and have been widely used as supports for many reactions. Many other polymeric materials are also used. These can be various other type of copolymers of styrene or with other polymers. The list includes cellulose, starch, polyalkanes, polyamides, poly(glycidyl methacrylate), polyisobutylene, polynorbomene, polyacrylamide, and others. In some instances, even glass was used. The more prominent support materials are presented below. 

Experimental procedure used to fabricate two-dimensional arrays of polymeric microlenses on glass substrates, (a) Cross-sectional view of packing cell used to deliver monodispersed polystyrene beads into two-dimensional array of cylindrical holes patterned in thin film of PR spin coated on bottom glass substrate, (b) Fabrication of microlenses with hemispherical and mushroom-shaped profiles by annealing sample at temperatures above glass transition temperature of polystyrene ( 93°C). The formation of a hemispherical shape was driven by the minimization of the surface free energy. (Source Lu, Y., Y.D. Yin, and Y.N. Xia. 2001. Advanced Materials, 13(1), 34-37. With permission.)... 

Polystyrene, expandable polystyrene (containing a volatile C4-C6 hydrocarbon), high impact polystyrene, styrene copolymers with acrylonitrile (SAN) and ABS, and poly(methyl methacrylate) are the main products of the suspeusion bead polymerization. PVC is the main polymeric material produced by suspension powder polymerization. 

As another example, let s consider the chemical reactions that are used to prepare ion exchange resins. These resins are composed of small polymer beads that can be used to exchange one ion for another in aqueous solutions. The polymer that is used in these applications is a cross-linked polystyrene. To make this material, styrene containing a small amount of divinylbenzene is polymerized. Each vinyl group of divinylbenzene can become part of a separate polymer chain, so these groups act as cross-links between chains. The resulting polymer is used in the form of small beads that are completely insoluble in typical solvents. 

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