Polystyrene in benzene solution

Hunston and Reischman showed that the contribution of 25 ppm of a 2 x 10 polystyrene in benzene solution to DR was negligible when added to 2.5 ppm of a 7 X 10 polystyrene (Fig. 3), demonstrating that a small amount of high-MW polymer dominates DR behavior in a mixture. ... 

Since this fluorescent labeling methodology is a living functionalization reaction, the resulting living fluorescent-labeled polymers can be used to initiate the polymerization of a second monomer to produce a block copolymer with the label at the block interface as discussed previously. For example, this procedure has been used to prepare polystyrene-Wock-poly(ethylene oxide) copolymers with both pyrene (60) (see Scheme 23) and naphthalene fluorescent groups at the interface between the two blocks [180-182]. Lithium was used as the counterion to prepare well-defined, quantitatively-ethylene oxide-functionalized polystyrenes in benzene solution [183]. However, under these conditions, it is not possible to polymerize ethylene oxide [183]. Therefore, it was necessary to add either dimethylsulfoxide [180, 181] or a potassium alkoxide [182] to promote ethylene oxide block formation as shown in Scheme 23. These diblock copolymers were fractionated to obtain pure diblock copolymer... 

Fig. 3. Universal behaviour of the normalized self-diffusion coefficient DJDq Dq is the diffusion coefficient at infinite dilution) as a function of the reduced concentration c/c, where c is the concentration at which the labelled chains start to overlap, for polystyrene in benzene solutions. The different symbols correspond to different molecular weights in the range 78000-750000. Full symbols correspond to labelled and unlabelled chains having the same molecular weight, while open symbols correspond to a frozen matrix (P>>N) for which a pure reptational behaviour is observed (from Ref. (19)).

Lin and Rosen extended these results, determining Rg and A2 of 160, 280, 420, and 660 kDa polystyrenes in benzene solutions of 40, 160, and 630 kDa polymethylmethacrylate(24). Lin and Rosen found that Rg decUnes as PMMA concentration is increased, the slope dRg/dc being more negative for the larger polystyrenes. Matrix concentrations extended up to 90 g/1. Over this range, Rg declined hy perhaps 16%. Within the limit of accuracy of the measurement, Rg c) was linear in the matrix concentration. There is no indication of a low but nonzero concentration region in which Rg of the polystyrene is independent of PMMA concentration. 

Table 10.2 Values for Kcj/R at the Indicated Values of 9 and Cj for Solutions of Polystyrene in Benzene at 546 nm...

Prepare a Zimm plot using the data in Table 10.2 and evaluate M, B,and for this solution of polystyrene in benzene. The effective wavelength in the medium is Xq/u = 546/1.501 = 364 nm for this experiment. 

To run the residence time distribution experiments under conditions which would simulate the conditions occurring during chemical reaction, solutions of 15 weight percent and 30 percent polystyrene in benzene as well as pure benzene were used as the fluid medium. The polystyrene used in the RTD experiment was prepared in a batch reactor and had a number average degree of polymerization of 320 and a polydispersity index, DI, of 1.17. 

Figure 3 shows the effect on the viscosity of polystyrene samples irradiated (X > 305 nm) in benzene solution in the presence of initiator I-III. The degradation of the polymer is caused by free radicals generated from the initiators. There is also a significant difference between the three initiators. Initiator I has a stronger absorption band between 300 and 400 nm than the... 

Figure 3. Intrinsic viscosity of polystyrene samples, irradiated in benzene solution in the presence of initiator I-III. Polystyrene concentration 7.69x10 2 M, photoinitiator concentration 2.31 x 10-3 Ml p Pure polystyrene initiator I initiator II A initiator III. (Reproduced with permission from Polym. Deg. Stability Ref. 21).

Figure 4. Intrinsic viscosity of polystyrene samples irradiated in benzene solution under various conditions. Polystyrene concentration 7.69x 10-2 M and initiator I concentration 3.12x 10-3 M. vacuum nitrogen saturated air saturated V oxygen saturated 3.12 3 / 3-tert-butyl-4-hydroxyanisole 3.12x 10-3 M 1.4-diazobicyclo(2.2.2)-octane (DABCO).

In Fig. 5.5 the same type of plot is given for results which were obtained by the above mentioned authors 166) on solutions of oligomers of polystyrene in benzene at 20° C. The full curve is drawn according to eq. (5.24) with the parameters MA = 954 and (W/[ ])M = - 10-5 10 10 cm2/dyne. This value of MA corresponds to sB = 8.8. This value is rather satisfactory, when compared with literature values ( 8) (169). At the same time, the value of ratio (M/[f ])oo for infinitely high molecular weight is lower than Tsvetkov s value 12 10-10 cm2/dyne (166), as obtained in bromoform . In this connection, it should be admitted that the value obtained in bromoform is higher than in any other solvent. On the other hand, it remains clear that the fit of Fig. 5.5 is less satisfactory, perhaps due to a considerable polydispersity of the samples, as reported by the said authors. Very recently, Frisman, Sibileva and Chebishyan (170) reported a fair agreement between the results of the... 

Some adducts may reduce the rate of propagation to such a low value that the pertinent chain will be considered "dead", at least within the time of the experiment. Studies of Welch (50) have shown that butyl lithium initiated growing polystyrene may associate with BuLi in benzene solution, and the associated ends are too unreactive to contribute to the polymerization. However, the associated ends are in equilibrium with the... 

Figure 4. Critical concentrations, g25, of phase separation for block copoly-mers and polymer mixtures in benzene solutions at 25°C as functions of the polystyrene molecular weight...

The only product obtained by the copolymerization of styrene and maleic anhydride in acetone was the alternating copolymer even in the presence of more than equimolar quantities of either styrene or maleic anhydride. However, as shown by the data in Table I, larger quantities were obtained than could be accounted for by the formation of the alternating copolymer when excess styrene was used for the copolymerization in benzene solutions. In addition to the precipitates, there was also a trace of benzene-soluble product, which was shown to be polystyrene by infrared spectrometric (28) and pyrolytic gas chromatographic techniques (26). 

K 17 Kurosaki, S., T. Sudo and S. Watanabe Sedimentation, diffusion and viscosity of polystyrene fractions in benzene solutions. J. Chem. Soc. Japan, Pure Chem. Sect. 73, 789 (1952). 

Figure 26 Variations Ae in electric permittivity versus E for solutions of methyl polymethacrylate in benzene (O) (0.0973 g/100 cm ) and isotactic) polystyrene in benzene (A) (0.1104 g/100 cm ) measured by Przeniczny at a frequency of 6.5 MHz at 20 °C [Measurements by Gregson have not confirmed the magnitude of these Ae E) values (Senior Reporter) ...

Poly(styryl)lithium (> 15,000) In benzene solution was reacted with excess ethylene oxide In the presence of N,N,N, N -tetramethyl-ethylenedlamlne (TMEDA, [TMEDA]/[Li] 3.2). After 12 days at 25-30 C, size exclusion chromatographic analyses Indicated no significant ethylene oxide polymerization. Hydroxyethylated polystyrene was recovered in essentially quantitative yleU. 

Problem 4.12 Given below are typical light scattering data for solutions of polystyrene in benzene (fio = 1.5130) with A = 4360 A at 25°C ... 

Problem 4.14 Measurements of excess scattering for a solution of polystyrene in benzene at 25 C with light of wavelength 4358 A yielded the following data... 

Rabek [504] found that anthracene sensitizes the degradation and photo-oxidation of polystyrene in solution. It also sensitizes the degradation of cis-polybutadiene in benzene solution. 

The method used to obtain these results is, however, not very convincing. It has not been proved that the samples of teams A and C are close enough to the Kuhnian state. Moreover, the temperatures of the solutions are different for teams A and C, and this introduces a systematic error in the results. Nevertheless, we shall adopt (15.3.46) as the best experimental expression for the asymptotic law relating the square radius of gyration to the molecular mass for polystyrene in benzene at 25 °C. On the other hand, for polystyrene in CS2, we shall adopt the older result7... 

The bulk polymerization of DAP has been studied at 60°C with azobisisobutyronittile as initiator (39). Branching of the polymer chains is confirmed by enhanced broadening of the molecular weight distribution imtil gdation occurred at about 25% conversion. In copolymerizations with styrene at 80°C with benzoyl peroxide as initiator the gel time increases with fraction comonomer in the feed. Both the yidd of gd and the styrene units in the gel increase with copolymerization time. Heating DAP prepolymer with styrene in benzene solution at 60—100°C with the initiators gives no gelation, but slow formation of polystyrene and copolymer. 

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