Polystyrene in carbon disulfide

When we determine values of 7 for benzene rings attached to polymers, we find that they are much shorter than for benzene itself they are in fact at the lower limit of usefulness of the direct method. We have found (3) that for the phenyl resonance of a low molecular weight polystyrene in carbon disulfide 7 is only about 0.4 0.1 sec. at 25°. For the backbone protons, 7 is even shorter and cannot be measured by the direct method. For the phenyl groups of poly-y-benzylglutamate in trifluoroacetic acid, 7 is 0.7 0.1 sec. Recently, more reliable values have been obtained for polystyrene by the spin echo method (72). For a polymer of molecular weight 63000 in tetrachloroethylene, three 7 X values could be resolved. At 25°, these were 0.033 sec. for the aliphatic protons, 0.076 sec. for the ortho protons and 0.20 sec. for the meta-para protons. The temperature coefficients for all three Tt values correspond to a heat of activation of about 3 kcal/mole. The differences in the absolute Tx values at the aromatic positions can be explained in terms of of differences in the sums of r e in equation (56). The shorter aliphatic Tj value probably reflects also a longer correlation time for backbone... 

The preparation of the starting material, poly(vinylacetophenone), may be carried out by a Friedel-Krafts reaction of polystyrene in carbon disulfide with acetyl chloride and aluminum chloride by the method of Kenyon and Waugh [95a]. 

These features are the same as those found in the earlier SANS work of Daoud et al. [I] on polystyrene in carbon disulfide. 

Figure 4.19. Reduced mean square radius of gyration, R, of polystyrene in carbon disulfide, plotted as a function of the polymer concentration c. Data were obtained in smaU-angle neutron scattering. The straight line has a slope of —1/4. (From Ref. 49.)...

A. Hiltner Yes. You just made an important point which is that this is a general phenomenon and should nc% be considered as typical of atactic polystyrene in carbon disulfide. Because the solvent obviously affects the thermodynamics, if one finds the proper solvent, any polymer should gel. Your other point which is that it could be intra- as well as intermolecular is absolutely correct, and we just see the manifestation as gelation when it s intermolecular and forms a netwtnk. That s why the overlap is necessary. 

Kockelbekgh and Smets 132) have used chloromethylated polystyrene dissolved in carbon disulfide in the presence of aluminium... 

Fig. 4. Correlation length as a function of polymer concentration measured by neutron scattering by Daoud et al. (1975). Closed symbols denote polystyrenes of two different molecular weights in deuterated benzene open symbols denote deuterated polystyrenes of two molecular weights in carbon disulfide.

Irie M, Iga R. 1986. Photoresponsive polymers 9. Photostimulated reversible sol gel transition of polystyrene with pendant azobenzene groups in carbon disulfide. Macro molecules 19(10) 2480 2484. 

An example of a cationic grafting reaction is the formation of a graft copolymer of polyisobuty-lene on polystyrene backbones. Polystyrene is chloromethylated and then reacted with aluminum bromide in carbon disulfide solution. This is followed by the introduction of isobutylene ... 

Ire and Iga demonstrated that photostimulated sol-gel transitions are possible with gels of a polystyrene copolymer in carbon disulfide solution that carry some azobenzene groups. The transitions are reversible and take place upon ultraviolet light irradiation. The polymer undergoes cis to trans isomerization of the pendant azobenzene groups with a 62% conversion for polymers containing as much as 10.5% of azo groups ... 

Figure 7.3(b) compares the experimental phase diagram of atactic polystyrene (at-PS) solution in carbon disulfide (CS2) [13-15]with theoretical calculations. This solution shows a TCP-type phase diagram, but CEP types were also reported for at-PS in... 

Francois and coworkers [137,138] reported on the synthesis of polystyrene-block-poly(p-phenylene) block copolymers via the anionic polymerization to poly styrene-block-poly (1,3-cyclohexadiene) and subsequent aromatization. The micellar assemblies and molecular dispersed free chains could be separated by size exclusion chromatography and with this method, the size of the spherical assemblies was found to be 30-50 A for the poly(p-phenylene) core, and 3-15 nm for the full micelle. By evaporating the solvent from solutions in carbon disulfide in moist air. 

The catalyst has been prepared by treating co(polystyrene-DVB) (1.8% cross-linked, 50-100 mesh) with anhydrous aluminum chloride in carbon disulfide, followed by addition of cold water (Neckers et aL, 1972). The polymeric catalyst is filtered off and washed successively with water, ether, acetone, and hot isopropanol, and finally dried in a vacuum oven. 

FIGURE 114 Isorefractivity of polystyrene (PS) in carbon disulfide (CS ) that is there is no excess scattering due to PS when dissolved in CS. In contrast, polybutadiene (PB) shows strong scattering in CS since its refractive index differs significantly from that of CS . 

In another procedure, the preparation of the polymer-supported scandium catalyst was performed according to Scheme 8.17 [70], Polystyrene, cross-linked with divinylbenzene, was treated with 5-phenylvaleryl chloride in carbon disulfide in the presence of aluminum trichloride. The carbonyl groups were then reduced using aluminum trichloride-lithium aluminum hydride in diethyl ether to afford double spacer resin. After sulfonation (chlorosulfonic acid/acetic acid), resin was treated with scandium(III) chloride in acetonitrile at room temperature to give the polymer-supported scandium chloride. Finally, it was treated with trifluo-romethanesulfonic acid to afford the immobilized triflate. 

The present procedure2 describes the conversion of resin-bound, primary aliphatic amines into isothiocyanates and the conversion of the latter into 3-aminothiophenes. The generation of isothiocyanates is related to known procedures,3 in which amines are first treated with carbon disulfide and the resulting dithiocarba-mates are desulfurized by treatment with a condensing agent (alkyl chloroformates, carbodiimides, lead or mercury salts, etc.). The presence of resin-bound isothiocyanates on the polystyrene support could be qualitatively ascertained by infrared spectroscopy (KBr-pellet strong absorption at 2091 cm-1). 

Surprising effects can also be observed when solvent mixtures are used to dissolve a polymer. There are examples where mixtures of two non-solvents act as a solvent vice versa, a mixture of two solvents may behave like a non-solvent. For example, polyacrylonitrile is insoluble in both, nitromethane and water, but it dissolves in a mixture of the two solvents. Similar behavior can be observed for polystyrene/acetone/hexane and poly(vinyl chloride)/acetone/carbon disulfide. Examples of systems where the polymer dissolves in two pure solvents but not in their mixture are polyacrylonitrile/malonodinitrile/dimethylforma-mide and poly(vinyl acetate)/formamide/acetophenone. These peculiarities are especially to be taken into account if one wants to adjust certain solution properties (e.g., for fractionation) by adding one solvent to another. 

Almost all electrophilic substitutions known to proceed in solution with isopropylbenzene can also be performed with polystyrene, using solvents such as nitrobenzene, carbon disulfide, or carbon tetrachloride. These substitutions include bromination [42], nitration [43,44], sulfonylation, Friedel-Crafts acylations [45 49], and alkylations... 

Polystyrene-Aluminum chloride." Aluminum chloride forms a water-stable complex with polystyrene-divinylbenzene (1.8%) copolymer denoted as (0 AICI3. In a typical preparation, the copolymer beads (59-100 mesh, 31.0 g.)are treated with carbon disulfide and then anhydrous aluminum chloride (7.5 g.). The mixture is stirred at reflux for 40 min. and then excess AICI3 is destroyed by cautious addition of water. The mixture is stirred until the original orange color fades to light yellow. The (P)-AIClj is filtered, washed with water, then successively with ether, acetone, hot iso-prnpanol, and ether, and finally dried in a vacuum oven for 18 hr. The complex is stable to the atmosphere for over one year. The anhydrous aluminum chloride can be released from the polymer by swelling with various solvents benzene, hexane, carbon disulfide. 

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