4- sty rene

Figure Bl.19.29. AFM image of poly sty rene/poly butadiene copolymer, showing lamellar stnicture. (Taken ftom [140], figure 1.)...

The soapless seeded emulsion copolymerization method was used for producing uniform microspheres prepared by the copolymerization of styrene with polar, functional monomers [115-117]. In this series, polysty-rene-polymethacrylic acid (PS/PMAAc), poly sty rene-polymethylmethacrylate-polymethacrylic acid (PS/ PMMA/PMAAc), polystyrene-polyhydroxyethylmeth-acrylate (PS/PHEMA), and polystyrene-polyacrylic acid (PS/PAAc) uniform copolymer microspheres were synthesized by applying a multistage soapless emulsion polymerization process. The composition and the average size of the uniform copolymer latices prepared by multistage soapless emulsion copolymerization are given in Table 11. 

Finally, ion chromatography can be used to determine the a-sulfo fatty acid esters. The chromatographic column is a nonpolar poly sty rene/divinylbenzene column and the ion pair reagent is 0.005 M ammonia. In order to reduce the elution time, acetonitrile is added as a modifier with increasing concentration. This gradient technique makes it possible to separate simultaneously ester sulfonates and disalts by chain length. Determination is achieved by standards with defined chain length [107]. 

Priddy, X), R Thermal Discoloration Chemistry of Sty rene-oo-Acrylonitrile. VoL 121, pp, 123-154. 

One of the requirements of this approach is that the analytes must be stable at the boiling point of the solvent, since the analytes collect in the flask. The solvent must show high solubility for the analyte and none for the sample matrix. Since this is one of the oldest methods of sample preparation, there are hundreds of published methods for all kinds of analytes in as many matrices. For example, XAD-2 resin (sty-rene-divinylbenzene) that was used to collect air samples to monitor current usage of pesticides in Iowa was Soxhlet-extracted for 24 h with hexane/acetone [22], This is common in environmental sample analysis, and one will see rows and rows of these systems in environmental laboratories. One disadvantage of Soxhlet extraction is the amount of solvent consumed, though modern approaches to solid sample extraction have tried to reduce the amount of solvent used. 

The use of phenolic polymers in photocrosslinkable systems usually involves multicomponent systems which incorporate polyfunctional low molecular weight crosslinkers. For example, Feely et al. [9] have used hydroxymethyl melamine in combination with a photoactive diazonaphthoquinone which produces an indene carboxylic acid upon irradiation to crosslink a novolac resin. Similarly, Iwayanagi et al. [10] have used photoactive bisazides in combination with poly(p-hydroxy-sty-rene) to afford a negative-tone resist material which does not swell upon development in aqueous base. 

Fig. 1 Chemical structures of the polymers commonly used for preparation of beads poly (styrene-co-maleic acid) (=PS-MA) poly(methyl methacrylate-co-methacrylic acid) (=PMMA-MA) poly(acrylonitrile-co-acrylic acid) (=PAN-AA) polyvinylchloride (=PVC) polysulfone (=PSulf) ethylcellulose (=EC) cellulose acetate (=CAc) polyacrylamide (=PAAm) poly(sty-rene-Wocfc-vinylpyrrolidone) (=PS-PVP) and Organically modified silica (=Ormosil). PS-MA is commercially available as an anhydride and negative charges on the bead surface are generated during preparation of the beads...

Examples of radiation-grafted PEMs poly(ethylene-flZf-tetrafluoroethylene)-gra/f-poly(sty-rene sulfonic acid) (ETFE-g-PSSA), 30 PVDF-g-PSSA, 31 and poly(tetrafluoroethylene-co-hexafluoropropylene)-g-PSSA (FEP-g-PSSA), 32. 

Fig. 2.1. Schematic presentation of species present in an emulsion polymerization (S=sty-rene monomer, R-X=growing polymer chain)...

The two products differ in polarity and thus in hydrophilicity.The acrylic acid-b-sty-rene-b-acrylic acid triblock copolymer exhibits amphiphilic properties and forms an emulsion in diiute sodium hydroxide solution where the acid groups are neutralized. 

Another type of multimonomer was prepared from poly(methacryloyl chloride) and allilamine, and was used in order to examine copolymerization process with sty-rene. ° The copolymerization was carried out in dioxane with AIBN as initiator. The basic reaction leads to the product with ladder-type blocks of allylmethacrylamide units, and blocks consist of styrene units ... 

Table IV. Various Quantum Yields in the Irradiation of Poly (sty rene-co-vinyl aromatic ketone)s at 313 nm in N2...

Leavens et al. (1996a, 1997) and Leavens and Bond (1996) further explored the metabolic interactions between butadiene and styrene in male B6C3Fj mice exposed to mixtures of butadiene and sty rene by inhalation. At steady state, significant inhibition of butadiene metabolism by styrene was observed with mixtures of 1000 ppm butadiene and 250 ppm styrene, but not with 100 ppm butadiene and 250 ppm styrene. Inhibition by butadiene of sty rene metabolism was evidenced by the significant increase in styrene blood concentrations (42% above that in mice exposed to styrene only) in the exposure to 1000 ppm butadiene and 250 ppm styrene. These authors concluded that while exposure to mixtures of sty rene and butadiene results in inhibition of metabolism of both sty rene and butadiene, interactive effects are seen only at high concentrations that are of little relevance to human exposure. 

Another kind of solid support that has gained more popularity is the surface-modified polypropylene, such as the Multipin crown and Microtubes. Reaction 3 was carried out on lightly and highly cross-linked polystyrene resins (1 % and >20% divinylbenzene, respectively), poly sty rene-PEG resin, and a surface-functionalized Microtube reactor.12 The reaction kinetics on these supports is compared in Figures 7.4 and 7.5. The reaction on the highly cross-linked polystyrene resin was shown to be slower than on other supports and the reaction on Microtube was faster than on polystyrene resins. 

Figure 5b. Line width vs. temperature for the system Poly sty rene-CCU.

Figure 2. Illustrative method for generating PMMA molecular weight and HDV calibration curves in TFE using a poly sty rene-HDV calibration curve in...

Subsequently, a resist system was reported that is composed of polymers containing recurrent acid-labile pendant groups in combination with an ar-ylonium salt-acid photogenerator (64-67). An example of the type of polymer used in this work is poly(p-tert-butyloxycarbonyloxystyrene) (t-BOC-sty-rene). 

A review of the chromatographic behavior of 90 penicillin and cephalspor-ins and their correlation to hydrophobicity has been published [339]. The current state of chromatographic methods submitted to the USP for com- plex antibiotics has been reviewed [340], A comparison has been made between poly(styrene-divinylbenzene) stationary phases and silica-based re-versed-phase sorbents for analysis of erthromycin and minocycline, and it was concluded that the nonsilica-based packings are more stable and ] reproducible [341]. The comparative retentions of ampicillin, amoxicillin,] and pencillin G was determined on Ci8, cyanopropyl-silica and poly(sty- rene-divinylbenzene), and nonbonded silica [342]. 

C. Hendrix, C. Wijsen, L. M. Yun, E. Roets, and J. Hoogmar-tens, Column liquid chromatogrpahy of cetadroxil on poly(sty-rene-divinylbenzene), J. Chromatogr., 628 49 (1993). 

The synthesis, characterization, and mechanical properties of a novel star block copolymer thermoplastic elastomer with eight poly(isobutylene-b-sty-rene) arms radiating from a calix[8]arene was recently reported by Jacob et al. [41]. The process involved the synthesis of eight arm star PIB by a method essentially identical to that described above, followed by sequential addition of S after the IB conversion has reached 95%. To minimize alkylation and to obtain high MW PS blocks, moderate TiCl4 concentration (0.059 mol 1 x) and a 2- to... 

The attachment of preformed polyethereal dendrons (e. g., 70, see Scheme 5.17), which have been functionalized at the focal point by reaction with p-(chloromethyl)sty-rene, has been shown1501 to undergo free radical copolymerization with styrene giving rise to polystyrene with appended benzyl ether dendritic wedges. 

Figure 7. Viscosity changes and polymer concentration for the reaction between hexamethylene diisocyanate and sty-rene-hydroxyethyl methacrylate copolymers in toluene at...

Figure 3. A comparison between the mechanical properties of poly(sty-rene) and a poly(styrene) braid. ( ) Compression-molded sample of PS.

Figure 8. Small-angle x-ray scattering (SAXS) data for poly ( sty rene-b-butadiene-b-styrene) blended with 20% polystyrene and cast from THF/methyl ethyl ketone (after Ref. 64)...

S-DMS refers to styrene-dimethylsiloxane diblock copolymers S-l refers to sty-rene-isoprene diblock copolymers S-l-S and I-S-I refer to styrene-isoprene-styrene and to isoprene-styrene-isoprene triblock copolymers, respectively and S-EO and EO-S-EO refer to styrene-ethylene oxide diblock copolymers and to ethylene oxide-styrene-ethylene oxide triblock copolymers, respectively. 

---