Polystyrenes types

Thermoplastic Elastomers. These represent a whole class of synthetic elastomers, developed siace the 1960s, that ate permanently and reversibly thermoplastic, but behave as cross-linked networks at ambient temperature. One of the first was the triblock copolymer of the polystyrene—polybutadiene—polystyrene type (SheU s Kraton) prepared by anionic polymerization with organoHthium initiator. The stmcture and morphology is shown schematically in Figure 3. The incompatibiHty of the polystyrene and polybutadiene blocks leads to a dispersion of the spherical polystyrene domains (ca 20—30 nm) in the mbbery matrix of polybutadiene. Since each polybutadiene chain is anchored at both ends to a polystyrene domain, a network results. However, at elevated temperatures where the polystyrene softens, the elastomer can be molded like any thermoplastic, yet behaves much like a vulcanized mbber on cooling (see Elastomers, synthetic-thermoplastic elastomers). 

Resins containing these functional groups are generally available in one or more forms for example, strong acid cation resin is typically a sulfonated polystyrene type, available either in the hydrogen form (H+ ) or in the sodium form (Na+). The sodium form of this resin is used for water softening. 

Siloxane containing polyester, poly(alkylene oxide) and polystyrene type copolymers have been used to improve the heat resistance, lubricity and flow properties of epoxy resin powder coatings 43). Thermally stable polyester-polysiloxane segmented copolymers have been shown to improve the flow, antifriction properties and scratch resistance of acrylic based auto repair lacquers 408). Organohydroxy-terminated siloxanes are also effective internal mold release agents in polyurethane reaction injection molding processes 409). 

In general, the acid-sorbing resins may be classified as high molecular weight polyamines or polyimines. Thus, the original Adams and Holmes material was a polymer of m-phenylenediamine. Cation Exchange materials include synthetic resins, such as sulfonated phenol-formaldehyde or polystyrene types, and sulfonated coal. Some manufacturers have a variety of sub-types which are considered superior for particular applications. 

In a similar way, Mizota et al. grafted polymer chains functionalized with sulfonic sites over a polystyrene-type polymer. As observed above, the flexibility of the polymer chains allowed better accessibility of the catalytic sites and this solid acid catalyst was ten times more active than the conventionally used cross-linked resin in the hydrolysis of sucrose (Scheme 2) [27]. 

Rohm and Flaas Company has developed Amberlite polymeric adsorbent resins that can be used to remove organic compounds from contaminated groundwater, aqueous wastes, and vapor-phase wastes. Amberlite XAD-4 is a crosslinked polystyrene-type polymer. It is hydrophobic and has no ionic functional groups incorporated into its resin structure. The material is most useful in removing low-molecular-weight organic substances from aqueous systems. Amberlite XAD-4 has been commercially available since the 1970s. 

Polymer-supported reagent. HMPT supported on a polystyrene-type resin is a catalyst for SN2 reactions5-7 and for reduction of ketones by NaBIi4.7 It also has a marked effect on the alkylation of ethyl acetoacetate with diethyl sulfate. In the presence of solid HMPT the enolales undergo 60 70% O-alkylation. In the absence of HMPT, the lithium enolate does not react and the sodium and potassium enolates undergo C-alkylation (90-100%). There is some difference in the effect of solid and liquid I1MPT The solid HMPT increases the reactivity of the K. enolate more than the liquid form, whereas the reverse is true with the Li enolate.8... 

Cross-linked polystyrene resins incorporating chiral amino acids were utilized as the chiral stationary phases (CSPs) in CLEC [6,21], Davankov et al. [12] reported the use of a resin incorporating L-proline in a polystyrene-type matrix. The resin was prepared by reacting L-proline with the chlormethylated styrene-divinyl-... 

Heterogeneous chiral catalysts are useful because of the easier separation of catalyst from the product and recovery process than homogeneous chiral catalysts. Heterogeneous chiral catalysts supported on polystyrene-type resin catalyse the highly enantioselective addition of dialkylzincs to aldehydes.17... 

Methyl Salicylate Dose forms, such as liniments or ointments containing methyl salicylate, should not be dispensed in polystyrene-type containers, as it is not stable. Accidental and deliberate injection causes severe and rapid salicylate poisoning because of its highly concentrated form and rapid absorption.68... 

It has to be noted that cross-linked resins containing the functional groups which are characteristic of all the polymeric compounds reported in this Section may be prepared in a similar way, by functionalizing previously prepared crosslinked resins, usually of polystyrene type 53). 

Tlie purpose of supports is similar to that of the structural promoters in aiming at u high meta) disper.sion and catalyst surface. Typical supports are alurttina and silica [15], but also inert supports such as carbon [65,66] or polystyrene-type polymers [67] have been investigated, giving highly-active iron or cobalt catalysts. 

Figure 22-30. Typical model for sorption of proUne enantiomers on L-proline or l-hydroxyproUne incorporating polystyrene type sorbents. (Reprinted from reference 150, with permission.)...

Such a process was attempted by treating the elastin from ligamentum nuchae first with several successive additions of pancreatic elastase and then further degrading the product with papain imtil all but a few per cent of the product was dialyzable through cellophane. The diffusate was then treated, in series, with a range of ion-exchange resins with varying internal pore diameter. The resins were of the suKonated polystyrene type, in bead form, and had nominal divinylbenzene (DVB) contents of 2 %, %,... 

Weakly acidic chelating resin, polystyrene type. ... 

Prepare 1 lb Dowex-1-chloride X-8 resin, 200-400 mesh. The same initial procedures can be used for any of the polystyrene type resins. 4-2. Suspend the resin in 2 liters distilled water. 

Ion-exchange chromatography is widely used to separate and analyze mixtures of amino acids. The most common ion-exchange resin used for this purpose is a sulfonic acid cation exchanger of the Dowex-50 (polystyrene) type. The structure of the resin is ... 

The acetate group is cleaved without benzyl ether deprotection under mild basic conditions using sodium methanolate in methanol. In this so-called Zemplen saponification, AMBERLITE IR120 is used, which is a gel-type strongly acidic cation-exchange resin of the sulfonated polystyrene type. 

An important group of substituted polystyrenes is that with ionic groups as substituents. The backbones of these polymers have covalently bound groups that are able to exist in ionic form. The presence of the ionic groups provides properties of ion exchanger, and the resins act as polyelectrolytes. Some of the groups introduced in polystyrene type ion exchangers are indicated in Table 6.6.4. 

Table 6.6.4. Functional groups introduced in polystyrene type ion exchange resins.

For a recent study describing the determination of site-site distance and site concentration within polymer beads of different polystyrene-type polymers see Marchetto, R., Cilli, E.M., Jubilut,... 

Thus, although they are of limited value, the NMR and ultraviolet data do support a polystyrene type structure and, when coupled with the infrared data, strongly suggest that the polymers are both polystyrenes. 

Maleated polystyrene, type Amount of aspen fiber in WPC (% w/w) Glass transition temperature (°C)... 

The packings available for use in HPLC are either of the cross-linked polystyrene type or of the controlled pore size glasses or silica. 

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