Polystyrene, porous

Cross-linked polystyrene porous particles (with 21 mol% DVB) have been prepared by the concentrated emulsion polymerization method, using either toluene or decane as the porogen and an aqueous solution of SDS as the continuous phase. Since toluene is a good solvent for polystyrene while decane is a nonsolvent , the morphologies obtained in the two cases were different. The particles based on toluene (with a volume fraction of dispersed phase of 78%) have very small pores which could not be detected in the SEM pictures. The pore size distribution, which has sizes between 20 and 50 A and was determined with an adsorption analyzer, almost coincides with that in a previous study [49] in which porous polystyrene beads have been prepared by suspension polymerization. In contrast, the porous particles based on decane have pore sizes as large as 0.1-0.3 pm, which could be detected in the SEM pictures [44a], and also larger surface areas (47 m2 g ) than those based on toluene (25 m2 g ). The main difference between the concentrated emulsion polymerization and the suspension polymerization consists of the much smaller volume fraction of continuous phase used in the former procedure. The gel-like emulsion that constitutes the precursor in the former case contains polyhedral cells separated by thin films of continuous phase. The polymerization of the cells does not... 

El-Gholabzouri, O., Cabrerizo, M.A., and Hidalgo-Alvarez, R., Streaming current of polystyrene porous plugs Solvent composition effect, J. Colloid Interf. Sci., 199, 38, 1998. 

Amberlite IRA-900 Rohm and Haas Trimethyl benzyl ammonium Cl- Polystyrene porous 100 0-14.0 16-50 500-1000... 

Diaion WA20 Mitsubishi Polyamine Free base Polystyrene porous 250 0-9 0 40-60 350-550... 

Tenax GC sorbent has a known upper temperature limit of350 °C. It is a commonly used adsobent because of its high upper temperature limit and low background on desorption. Tenax is a porous polymer of 2,6-diphenyl phenol and has a packed density of approximately 0.22 g/mL (60/80 mesh). Chromosorb 106 is a cross-linked polystyrene porous polymer. It has a published upper temperature limit of 250 °C and a packed density of approximately 0.39 g/mL (60/80 mesh). Porapak N sorbent is a styrene/divinyl benzene porous polymer in wich vinyl pyrollidone is added to increase its polarity. The published upper temperature limit of Porapak N is 190 °C. Porapak N has a packed density of approximately 0.42 g/mL (60/80 mesh). Carbosieve B sorbent is a synthetic carbon molecular sieve and is one of the most retentive solid adsorbents available. It has an upper temperature limit of at least 400 °C and a packed density of approximately 0.22 g/mL (60/80 mesh). 

Two classes of micron-sized stationary phases have been encountered in this section silica particles and cross-linked polymer resin beads. Both materials are porous, with pore sizes ranging from approximately 50 to 4000 A for silica particles and from 50 to 1,000,000 A for divinylbenzene cross-linked polystyrene resins. In size-exclusion chromatography, also called molecular-exclusion or gel-permeation chromatography, separation is based on the solute s ability to enter into the pores of the column packing. Smaller solutes spend proportionally more time within the pores and, consequently, take longer to elute from the column. 

Porous polymers with large 77 K nitrogen surface areas also have infenor methane uptakes. For example Dow XV 43546, a porous polystyrene with a 77 K nitrogen BET area of 1600 mVg has a methane uptake of 67 mg/g at 25°C, 3.4 MPa, whereas Takcda HGK 971 carbon of similai" 77 K nitrogen surface area has an uptake of 116 mg methane per g. Rohm and Haas Amberlite porous polymers give similarly lower than expected methane uptakes. 

A porous polystyrene-divinylbenzene gel is produced by suspension polymerization in an aqueous system with incorporation of more than 5 mol% initiator to a total amount of styrene and divinylbenzene with an inert organic solvent as diluent and porogen (24). 

Modern SEC columns are packed with material other than polystyrene gels, such as porous silica particles or highly cross-linked styrene-divinylbenzene copolymers. Because of improvements in speed and resolution, the term SEC is sometimes replaced by the term high-performance size-exclusion chromatography (HPSEC). 

PMMA, on the unmodified porous glass and silica gel, and the universal calibration curves for polystyrenes and poly(methyl methacrylates) did not coincide (10,12,19). 

A research group in Lehigh University has extensively studied the synthesis and characterization of uniform macroporous styrene-divinylbenzene copolymer particles [125,126]. In their studies, uniform porous polymer particles were prepared via seeded emulsion polymerization in which linear polymer (polystyrene seed) or a mixture of linear polymer and solvent were used as inert diluents [125]. The average pore diameter was on the order of 1000 A with pore volumes up to... 

Gas-filled plastics are polymer materials — disperse systems of the solid-gas type. They are usually divided into foam plastics (which contain mostly closed pores and cells) and porous plastics (which contain mostly open communicating pores). Depending on elasticity, gas-filled plastics are conventionally classified into rigid, semi-rigid, and elastic, categories. In principle, they can be synthesized on the basis of any polymer the most widely used materials are polystyrene, polyvinyl chloride, polyurethanes, polyethylene, polyepoxides, phenol- and carbamideformaldehyde resins, and, of course, certain organosilicon polymers. 

Hollow and porous polymer capsules of micrometer size have been fabricated by using emulsion polymerization or through interfacial polymerization strategies [79,83-84, 88-90], Micron-size, hollow cross-linked polymer capsules were prepared by suspension polymerization of emulsion droplets with polystyrene dissolved in an aqueous solution of poly(vinyl alcohol) [88], while latex capsules with a multihollow structure were processed by seeded emulsion polymerization [89], Ceramic hollow capsules have also been prepared by emulsion/phase-separation procedures [14,91-96] For example, hollow silica capsules with diameters of 1-100 micrometers were obtained by interfacial reactions conducted in oil/water emulsions [91],... 

Adamski, RP Anderson, JL, Configurational Effects on Polystyrene Rejection from Micro-porosou Membranes, Journal of Polymer Science Part B Polymer Physics 25, 765, 1987. Adler, PM, Porous Media, Geometry and Transports Butterworth-Heinemann Boston, 1992. Afeyan, NB Fulton, SP Regnier, FE, Perfusion Chromatography Packing Materials for Proteins and Peptides, Journal of Chromatography 544, 267, 1991. 

The other main support used for solid base catalysts is polystyrene, which while it does not have a well-defined porous structure, does swell in solvents providing an accessible high surface area on which to carry out reactions. One common method of chemically attaching groups to polystyrene involves incorporation of specific amounts of styrene contain-... 

This paper will be limited to a discussion of our packed column studies in which we have addressed attention to questions regarding, (a) the role of ionic strength and surfactant effects on both HDC and porous packed column behavior, (b) the effects of pore size and pore size distribution on resolution, and (c) the effects of the light scattering characteristics of polystyrene on signal resolution and particle size distribution determination. 

Figure 6. Effect of ionic strength on Rp for different polystyrene particle sizes using the porous Fractosil system (2A).

Figure 7. Comparison of polystyrene calibration curves for HDC and porous Fractosil systems (eluant ionic strength, 7.29/wM AM A (O) HDC ( 2) Fractosil)...

Polymer rod carrier material Porous glass Polymer type Polystyrene- divinylbenzene... 

Suitable PLOT columns for the determination of vinyl chloride monomer in PVC include 15.00 m, 0.53 mm bonded polystyrene-divinyl benzene and 30 m, 0.53 mm porous divinyl benzene homopolymer types. Typical responses for vinyl chloride monomer standards (0.06, 0.19 and 0.31 mg/1) in N,N-d imethylaceta-mide expressed as mg/kg vinyl chloride (PVC sample) using the 30 m homopolymer column and flame ionisation detection are shown in Figure 38. An automatic static headspace sampler was employed. 

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