Polystyrene, copolymers solubility

The IR spectra of all three polymers are recorded and compared with one another.The incorporation of monomeric units of 4-vinylpyridine can also be demonstrated by nitrogen analysis of the block copolymer.The solubility behavior is also determined. Po-ly(4-vinylpyridine) is soluble in pyridine, methanol, and chloroform, but insoluble in toluene and diethyl ether it swells considerably in water. On the other hand, the block copolymer, like polystyrene, is soluble in pyridine, chloroform, and toluene but unlike polystyrene, it swells significantly in methanol. 

In this section the use of polystyrene and copolymers of styrene with various cross-linking agents as supports for solid-phase organic synthesis is discussed. Copolymers of styrene with divinylbenzene are the most common supports for solid-phase synthesis. Depending on the kind of additives used during the polymerization and on the styrene/divinylbenzene ratio, various different types of polystyrene can be prepared. However, non-cross-linked polystyrene has also been used as a support for organic synthesis [10,16-22], Linear, non-cross-linked polystyrene is soluble in organic solvents such as toluene, pyridine, ethyl acetate, THF, chloroform, or DCM, even at low temperatures, but can be selectively precipitated by the addition of methanol or water. 

The polymeric oxazaborolidine prepared from the linear copolymer of 29 and styrene was used in membrane reactor and resulted in high total turnover number with high enantioselectivity [44]. Another polystyrene-based soluble polymeric oxazaborolidine 38 was used in the same system. Polysiloxanes are also useful polymeric supports of catalyst 39 for the same purpose [45]. 

Soluble polystyrene supports differ from the terminally functionalized PEGs and polyethylene oligomers discussed above in that the catalyst moieties are attached to polystyrene via pendant groups, the loading of which can affect both the catalyst activity and separability. One example of a simple polystyrene-supported catalyst is the polystyrene copolymer-supported quaternary ammonium salts 66 and 67 [ 103]. These copolymers can be prepared with varying ratios of the styrene unit in the copolymer - the most active catalysts had 20-40 mol% of the vinylbenzylammonium groups in the copolymers. The utility of these catalysts was studied in a variety of solvents in the addition reaction of glycidyl methacrylate and carbon dioxide (Eq. 23). Polar solvents were most useful. The necessary polymer supports for preparation of catalysts 66 and 67 were prepared from chloromethylstyrene-styrene or chloromethyl-styrene-iV,JV-dimethylacrylamide copolymers that were in turn prepared by radical polymerization of the styrene or acrylamide monomers. The catalysts were recycled up to four times with small (ca. 6%) decreases in activity - de-... 

Sodium DVB/acrylates copolymer Sodium hyaluronate Sodium polyacrylate starch Sodium polymethacrylate Sodium polystyrene sulfonate Sodium PVM/MA/decadiene crosspolymer Sodium styrene/acrylates copolymer Sodium tauride acrylates/acrylic acid/acrylonitrogens copolymer Soluble collagen Starch/acrylates/acrylamide copolymer Starch diethylaminoethyl ether Steareth-10 allyl ether/acrylates copolymer Stearylvinyl ether/MA copolymer ... 

Polystyrene (PS) and polyisoprene (PI) form block copolymers with PA in the presence of Ti(OBu)4 catalysts [83-85]. The two copolymers are prepared similarly. For instance, styrene is first initiated by n-BuLi (typically 0.05 M) in an anionic polymerization. A lithiated polystyiyl anion can then displace one butoxy group from the titanium center to form a new Ti-C bond, which serves as the active site for the subsequent acetylene polymerization. However, before acetylene was added, this polymeric catalyst was often aged for 1 day (PS) or 2 days (PI). The acetylene polymerization was then carried out under dilute conditions so as to minimize side reactions. In this manner, acetylene can be polymerized through the Ti(UI) catalyst, forming an AB diblock copolymer. In the case of polystyrene, less than 20 wt% of PA in the copolymer renders the copolymer soluble. Gels that were not soluble could be pressed into thin films for characterization. 

These tests are of limited value although Bird has described a simple thermal test for the identification of plastic films, (Method 105). The above tests are of limited value nowadays becaused of the wide range of polymers now being manufactured and certainly are probably of no value in the case of copolymers. Conventional low impact polystyrene is soluble in hot toluene, whereas high density polyethylene or propylene have little or no solubility in this solvent. However, if the polystyrene contains some copolymerized butadiene, as occurs in the case of high impact polystyrenes, then due to the presence of crosslinked gel, the polymer would not completely dissolve in hot toluene. So even in the case of simple polymers solubility tests are of limited value and for them to provide any useful information required detailed knowledge. Polystyrene on the other hand, unlike the polyolefins when it is held in a flame, due to its aromatic nature... 

The organic and aqueous phases are prepared in separate tanks before transferring to the reaction ketde. In the manufacture of a styrenic copolymer, predeterrnined amounts of styrene (1) and divinylbenzene (2) are mixed together in the organic phase tank. Styrene is the principal constituent, and is usually about 90—95 wt % of the formulation. The other 5—10% is DVB. It is required to link chains of linear polystyrene together as polymerization proceeds. DVB is referred to as a cross-linker. Without it, functionalized polystyrene would be much too soluble to perform as an ion-exchange resin. Ethylene—methacrylate [97-90-5] and to a lesser degree trivinylbenzene [1322-23-2] are occasionally used as substitutes for DVB. 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

Some commercial durable antistatic finishes have been Hsted in Table 3 (98). Early patents suggest that amino resins (qv) can impart both antisHp and antistatic properties to nylon, acryUc, and polyester fabrics. CycHc polyurethanes, water-soluble amine salts cross-linked with styrene, and water-soluble amine salts of sulfonated polystyrene have been claimed to confer durable antistatic protection. Later patents included dibydroxyethyl sulfone [2580-77-0] hydroxyalkylated cellulose or starch, poly(vinyl alcohol) [9002-86-2] cross-linked with dimethylolethylene urea, chlorotria2ine derivatives, and epoxy-based products. Other patents claim the use of various acryUc polymers and copolymers. Essentially, durable antistats are polyelectrolytes, and the majority of usehil products involve variations of cross-linked polyamines containing polyethoxy segments (92,99—101). 

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. 

The most frequently used organic supports are polystyrene and styrene-divinylbenzene copolymer beads with functional groups such as diphenylpho.sphine covalently bonded. The polymer-anchored catalyst complex can then be obtained, for example, by displacement of a ligand already co-ordinated to a soluble metal complex (Cornils and Herrmann, 1996) ... 

PVA Particles. Dispersions were prepared in order to examine stabilization for a core polymer having a glass transition temperature below the dispersion polymerization temperature. PVA particles prepared with a block copolymer having M PS) x 10000 showed a tendency to flocculate at ambient temperature during redispersion cycles to remove excess block copolymer, particularly if the dispersion polymerization had not proceeded to 100 conversion of monomer. It is well documented that on mixing solutions of polystyrene and poly(vinyl acetate) homopolymers phase separation tends to occur (10,11), and solubility studies (12) of PS in n-heptane suggest that PS blocks with Mn(PS) 10000 will be close to dissolution when dispersion polymerizations are performed at 3 +3 K. Consequently, we may postulate that for soft polymer particles the block copolymer is rejected from the particle because of an incompatibility effect and is adsorbed at the particle surface. If the block copolymer desorbs from the particle surface, then particle agglomeration will occur unless rapid adsorption of other copolymer molecules occurs from a reservoir of excess block copolymer. 

In the absence of polymer the sediment volume of silica depends on the non-solvent fraction of the medium as shown in Figure 6. The sediment volume assessment of steric stabilization behavior of the copolymers is illustrated in Figures 7a to 7c. At low styrene contents, both the random and block copolymers show a steady increase in sediment volume as the non-solvent content is raised up to the phase separation value. With polystyrene and random copolymers of high styrene content, the sediment volume stays largely constant with alteration in the non-solvent fraction until the theta-point is approached and then continues to become larger as the limit of solubility is reached. In Figure 7b only the data points of RC 86 are shown, RC 94 giving almost identical values. 

As the final products—polystyrene-h-polyivinylperfluorooctanoic ester)— form micelles in tetrahydrofuran (THF) as well as in DMF, there are not direct GPC data to characterize molecular parameter. For this reason, we employed esterification of the hydroxylated block copolymers with benzoylchloride as a model reaction to obtain a comparable product with molecular solubility that can easily be characterized by DMF-GPC. The GPC data from PSB-II—our largest and therefore most sensitive block copolymer—are summarized in Table 10.2. Results for all the other polymers are similar. 

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