Polystyrene in cyclohexane

The osmotic pressure of solutions of polystyrene in cyclohexane was measuredf at several different temperatures, and the following results were obtained ... 

Krigbaumf measured the second virial coefficient of polystyrene in cyclohexane at several different temperatures. The observed values of B as well as some pertinent volumes at those temperatures are listed below ... 

Figure 10.8 shows two sets of data plotted according to these conventions, after correction for the effect of interference. In Fig. 10.8a, HC2/T is plotted against C2 for three different fractions of polystyrene in methyl ethyl ketone. Figure 10.8b shows Kc2/Rg versus C2 for solutions of polystyrene in cyclohexane at five different temperatures. These results are discussed further in the following example.

Figure 10.8 Light-scattering data plotted to give slope-intercept values which can be interpreted in terms of M and B. (a) Polystyrene in methyl ethyl ketone. [From B. A. Brice, M. Halwer, and R. Speiser,/. Opt. Soc. Am. 40 768 (1950), used with permission.] (b) Polystyrene in cyclohexane at temperatures indicated. Units of ordinates are given in Example 10.4. [Reprinted with permission from W. R. Krigbaum and D. K. Carpenter,7. Phys. Chem. 59 1166 (1955), copyright 1955 by the American Chemical Society.]...

The results reported by Helary and Fontanille 84) provide an illustration of the above principles. Coordination of lithium polystyrene in cyclohexane by TMEDA increases the propagation rate for c = 8.3 mM but decreases for c = 0.92 mM. This is seen in the plots shown in Fig. 22. 

The effect of tetramethyl tetraaza cyclotetradecane, TMTCT, on the behaviour of lithium polystyrene in cyclohexane was investigated recently 149). 

Reciprocals of the critical temperatures, i.e., the maxima in curves such as those in Fig. 121, are plotted in Fig. 122 against the function l/x +l/2x, which is very nearly 1/x when x is large. The upper line represents polystyrene in cyclohexane and the lower one polyisobutylene in diisobutyl ketone. Both are accurately linear within experimental error. This is typical of polymer-solvent systems exhibiting limited miscibility. The intercepts represent 0. Values obtained in this manner agree within experimental error (<1°) with those derived from osmotic measurements, taking 0 to be the temperature at which A2 is zero (see Chap. XII). Precipitation measurements carried out on a series of fractions offer a relatively simple method for accurate determination of this critical temperature, which occupies an important role in the treatment of various polymer solution properties. 

The results of intrinsic viscosity measurements for four polymer-solvent systems made at the -temperature of each are shown in Fig. 141. The four systems and their -temperatures are polyisobutylene in benzene at 24°C, polystyrene in cyclohexane at 34°C, poly-(di-methylsiloxane) in methyl ethyl ketone at 20°C, and cellulose tricapry-late in 7-phenylpropyl alcohol at 48°C. In each case a series of poly-... 

Fig. 141.—Double logarithmic plot of [77]0 against M for several polymer series polyisobutylene in benzene at 24°C, O polystyrene in cyclohexane at 34°C, cellulose tricaprylate in T-phenylpropyl alcohol at 48 C, Q and...

Figure 3 Radius of gyration, Rg, and hydrodynamic radius, Rh, versus temperature for polystyrene in cyclohexane. Vertical line indicates the phase separation temperature. 

The same authors then discuss the determination of the entire molar mass distribution from sedimentation velocity runs via scaling laws for the polymer polystyrene in cyclohexane, where the scaling law is also known [78] ... 

Reaction of the bis-chelate complex 149 and various bis(arylalkyl)barium complexes generates heteroleptic barium complexes with one chelate and one reactive arylalkyl ligand 164. The homoleptic and heteroleptic barium complexes both induce living polymerization of styrene to atactic polystyrene in cyclohexane solution. The fact that no stereocontrol is observed during polymerization despite the presence of the chiral carbanionic ligands is... 

In this paper we briefly describe the apparatus and experimental method, then consider the interactions between i) layers of polystyrene in cyclohexane under poor-solvent and ii) 0 - solvent conditions,iii) the interactions between adsorbed PEO layers in a good (aqueous) solvent and iv) the surface forces between layers of adsorbed poly-L-lysine, a cationic polyelectrolyte, in aqueous salt solutions. We consider briefly the implications of our results for the current theoretical understanding. 

This method was also employed by Chu et al. 2 2) who investigated the effects of long range correlation for a critical mixture of polystyrene in cyclohexane at small temperature intervals from the phase seperation temperature. 

The interactions between solvent and polymer depend not only on the nature of the polymer and type of solvent but also on the temperature. Increasing temperature usually favors solvation of the macromolecule by the solvent (the coil expands further and a becomes larger), while with decreasing temperature the association of like species, i.e., between segments of the polymer chains and between solvent molecules, is preferred. In principle, for a given polymer there is a temperature for every solvent at which the two sets of forces (solvation and association) are equally strong this is designated the theta temperature. At this temperature the dissolved polymer exists in solution in the form of a nonexpanded coil, i.e., the exponent a has the value 0.5. This situation is found for numerous polymers e.g., the theta temperature is 34 °C for polystyrene in cyclohexane, and 14 °C for polyisobutylene in benzene. 

Use these data to evaluate the constants in the Staudinger-Mark-Houwink equation. Are the values obtained consistent with the known facts that 35.4°C is the Flory (0) temperature for polystyrene in cyclohexane while benzene is a good solvent for polystyrene at 40°C. 

Fig. 7. PDC-calibration curves for polystyrene in cyclohexane measured 3> at eight temperatures, as indiciated, and an overall rate of the column liquid of 15 cm3/h (ordinate is normalized as indicated). The 15 °C-calibration curve dyn is measured, whereas the dashed curve 15 °C therm is extrapolated from the measured part of the dyn curve (cf. Fig. 8), and corresponds to reversible-thermodynamic equilibrium of the PDC-column. The difference between both curves shows a pronounced PDC-effect at 15 °C for P = 1082. Elution volume V = Ve and zero volume V0 = are expressed in counts (1 count = 0.51423 cm3). For the definition of r0 see Eq. (5 b)...

Figure 5. Dissymmetry ratio IiS/I1S5 vs. concentration of polystyrene in cyclohexane at different temperatures above the phase-separation temperature...

Figure 6. Cloud-point curve for polystyrene in cyclohexane (%) determined from light scattering and (M) determined visually. The arrows indicate (from left to right) maximum of the cloud-point curve, maximum of the dissymmetry ratiof critical point.

Figure 7. Kinematic viscosity vs. temperature of polystyrene in cyclohexane. Numbers indicate wt % polystyrene.

S.W. Provencher, J. Hendrix, L. DeMayer and N. Paulussen, Direct determination of molecular-weight distributions of polystyrene in cyclohexane with photon correlation spectroscopy, J. Chem. Phys. 69 (1978) 4273-4276. 

Er. Gulari, Es. Gulari, Y. Sunashima and B. Chu, Polymer diffusion in a dilute theta solution, 1, Polystyrene in cyclohexane, Polymer 20 (1979) 347-355. 

Figure 4 shows a plot of the static expansion factor (o ) as a function of the relative temperature 0/T, where a is defined as Rg(T)/Rg(0) and r is the number of residues that may be one monomer unit or a number of repeat units. When T < 0 (water is a good solvent for PNIPAM), the data points are reasonably fitted by the line with r = 105 calculated on the basis of Flory-Huggins theory [15]. Similar results have also been observed for linear polystyrene in cyclohexane [25,49]. The theory works well in the good-solvent region wherein the interaction parameter (x) is expected to be... 

For fixed values of the molecular weight M and volume fraction of polystyrene in cyclohexane , the depletion contribution to the total potential is calculated according to Eq. [6], which involves complete penetration of the free polymer into the adsorbed layer, and is shown in Fig. 2. The range of this contri-... 

Fig. 3. Temperature dependence of the limiting volume fraction, required for the onset of phase separation for different molecular weights of the free polymer. (I), 36,000 (ff), 82,000 (III), 122,000 (IV), 176,000 (V), 490,000. Initial concentration of particles corresponds to p/pB = 0.05. System polyisobutene-stabilized silica particles and polystyrene in cyclohexane. The values of the parameters are as in Fig. 2.

In cyclohexane geminate recombination occurs very efficiently and the observation of polymer ions is rather difficult [57, 58]. However, when the electron scavenger such as chloroform and carbon tetrachloride was added to the solution of polystyrene in cyclohexane, a weak, broad absorption band with a maximum at lOOOnm due to dimer cation of benzene was observed. The dimer cation radical might be produced by the hole migration, along the polymer chain, from a radical cation to a site suitable for the dimer-cation formation [59]. 

Riseman (139) or Kuhn and Kuhn (153 , 153"). For the sake of comparison, Fig. 12 also shows the theta-solvent intrinsic viscosities of polystyrene in cyclohexane [experimental valuesofKRiGBAUMandFuoRY (149), small black points theoretical values, broken line] and the theoretical intrinsic viscosities of rigid ellipsoids with axial ratios p = M/500 (chain curve). As a matter of course, the chain curve reduces to the Einstein value of [rf in the range of M below500 [see, for example, Petehlin (16) ]z. 

Comparison of these potentials with those for the terminally anchored chains shows the interaction to be relatively weak. For example, experiments with polystyrene in cyclohexane, which does not adsorb on mica, yielded no detectable forces between mica surfaces because of the polymer (Luckham and Klein, 1985). Indeed, estimates of the potential from Eq. (130) at the experimental conditions fall several orders of magnitude below the detection limit for the instrument. 

Ratzsch, M. Kruger, B. Kehlen, H., "Cloud-Point Curves and Coexistence Curves of Several Polydisperse Polystyrenes in Cyclohexane," J. Macromol. Sci., Chem., A27, 683 (1990). 

The chains have nearly ideal conformations at the -temperature because there is no net penalty for monomer-monomer contact. Polystyrene in cyclohexane at = 34.5 C is an example of a polymer-solvent pair at the -temperature. 

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