Tracer diffusion polystyrene

Figure 12.16 Ratio of polystyrene tracer diffusion coeflScient (D,) in toluene swollen PMMA gel to diffusion coefficient of polystyrene in dilute toluene solution ( ) (/i ) values for PS tracer in PMMA solutions. Reproduced with pennission from the American Chemical Society from Ref. [S3]...

N. Nemoto, M. Kishine, T. Inoue, T. Osaki. Tracer diffusion of linear polystyrene in entanglement networks. Macromolecules 22 659-664, 1990. 

N. A. Rotstein, T. P. Lodge. Tracer diffusion of linear polystyrenes in poly-(vinyl methyl ether) gels. Macromolecules 25.T 316-1325, 1992. 

Measurements of diffusion of tracer polymers in ordered block copolymer fluids is another potentially informative activity, since molecular diffusion is one of the most basic dynamic characteristics of a molecule. Balsara, et al. have measured the retardation of diffusion due to ordering in the diffusion of polystyrene tracer homopolymers in polystyrene-polyisoprene matrices of various domain sizes [167]. Measurement of the tracer diffusion of block copolymer molecules will also be important. Several interesting issues are directly addressable via measurements... 

Fig. 10.12 The molecular-weight dependence of the tracer diffusion constant obtained for the nearly monodisperse polystyrene samples in a polystyrene matrix of molecular weight P = 2 X 10 at 174°C. The solid line represents Dq = 0.008M . Reproduced, by permission, from Ref. 28.

Nemoto, N (1989) Tracer diffusion of linear polystyrenes in entanglement networks, paper 18, Macromolecular Chem Section, 1989 Int Chem Cong Pacific Basin Soc, Hawaii Dec 17-22... 

Wheeler, et al. [124] studied tracer diffusion of linear polystyrenes having molecular weights 65, 179, 422, and 1050 kDa (with M /M < 1.1) through a 1.3 MDa polyvinyl-methylether matrix polymer, 1.6, in orthofluorotoluene at concentrations 1-100... 

Figure 4.24. Diffusion coefficients as functions of the composition in the miscible blend polystyrene-poly(xylenyl ether) (PS-PXE) at a temperature 66 °C above the (concentration-dependent) glass transition temperature of the blend, measured by forward recoil spectrometry. Squares represent tracer diffusion coefficients of PXE (VpxE = 292), circles the tracer diffusion coefficients of PS and diamonds the mutual diffusion coefficient. The upper solid line is the prediction of equation (4.4.11) using the smoothed curves through the experimental points for the tracer diffusion coefficients and an experimentally measured value of the Flory-Huggins interaction parameter. The dashed line is the prediction of equation (4.4.11), neglecting the effect of non-ideality of mixing, illustrating the substantial thermodynamic enhancement of the mutual diffusion coefficient in this miscible system. After Composto et al. (1988).

Although cannot be measured in DLS, a closely related tracer diffusion coefficient Dj can be measured. In the tracer diffusion, the motion of a labeled solute called a probe or a tracer is traced selectively. A second solute called a matrix is added to the solution and its concentration is varied, whereas the concentration of the probe molecules is held low. The matrix must be invisible, and the probe must be visible. We can give a large contrast between the matrix and probe by choosing a pair of solvent and matrix that are nearly isorefractive, i.e., having the same refractive index. Then, the light scattering will look at the probe molecules only. For instance, we can follow the tracer diffusion of polystyrene in a matrix solution of poly(dimethyl siloxane) in tetrahydrofuran. 

Figure 4.41. Tracer diffusion coefficient Di of polystyrene in solutions of matrix polymer, poly(vinyl methyl ether), in o-fluorotoluene at various concentrations of the matrix polymer, plotted as a function of molecular weight Mps of polystyrene. The solvent is isorefractive with the matrix polymer. The concentration of the matrix polymer and the slope obtained in the best fitting by a power law (straight line) are indicated adjacent to each plot. (From Ref. 53.)...

F ure 12.15 Diffusion coefficient of polystyrene tracer in polyvinyl methyl ether gels as a function of tracer molecular weight. Diffusion coefficients normalised by ratio of molecular weight between crosslinks of gels. Reprinted with permission from [52]. Copyright 1992 American Chemical Society... 

We have used forward recoil spectrometry to measure the mutual diffusion and tracer diffusion coefficients, D and D, in the miscible polymer blend of deuterated polystyrene (d-PS) poly(xylenyl ether) (PXE). Using the fast theory of mutual diffusion, D is related to the D, degree of polymerization N, and volume fraction of the individual blend components by,... 

Nemoto, et al. report sedimentation and tracer diffusion of dilute polymethylmethacrylate probes in dilute and nondilute polystyrene thiophenol(24,25). Polystyrene and thiophenol are isopycnic, permitting s of PMMA probes in polystyrene thiophenol to be determined unambiguously with ultracentrifugation. 

Figure 5.1 (a) Self-diffusion of tetrahydrofuran, and (b) tracer diffusion of hexafluorobenzene through tetrahydrofuran polystyrene for polystyrene molecular weights (O) 10, (0) 37.4, ( ) 179, (A) 498, and (V) 1050 kDa, showing Ds does not depend on polymer molecular weight. Original measurements from von Meerwall, et... 

An exemplary early study of tracer diffusion is shown in Figure 8.16, based on measurements by Leger, et al, who examined linear polystyrene benzene with FRS, comparing self-diffusion of 245 and 599 kDa chains with tracer diffusion... 

Several authors have explored tracer diffusion for the case that M and P are very different. By examining diffusion of photolabeled polymers through unlabeled homologous polymers, questions of thermodynamic incompatibility between the tracer and matrix chains may be almost entirely eliminated. Forced Rayleigh scattering was employed by Nemoto and collaborators to examine labeled tracer polystyrenes in polystyrene dibutylphthalate mixtures(48,49). Nemoto, et al. 

Figure 8.30 Nemoto, et al. s measurements of self- and tracer diffusion of photo-labeled polystyrene through unlabeled 40 wt% polystyrene dibutylphthalate(48). Systems with ( ) F M are connected by a dashed line. Dg for systems with (O) M/P > 5 and ( ) self-diffusion measurements follow the solid lines.

Diffusion through toluene solutions of unlabeled polystyrenes by dye-labeled polystyrene tracers was examined by Kim, et a/. (52). The objective of the original experiments was to test predictions that Ds should be independent of matrix M whenever M/P > 1. Matrix polystyrenes had 5 < M < 8400 kDa probe polystyrenes had 10 < P < 1800 kDa. Figure 8.33 shows the dependence of Ds on M for three probes (51, 900, 390 kDa from top to bottom) and multiple... 

B. Hanley, M. Tirrel, and T. P. Lodge. The behavior of the tracer diffusion coefficient of polystyrene in isorefractive solvents composed of polyvinyl methyl ether and o-fluorotoluene. Polym. Bull. Berlin, 14 (1985), 137-142. 

T. P. Lodge, P. Markland, and L. M. Wheeler. Tracer diffusion of 3-arm and 12-arm star polystyrenes in dilute, semidilute, and concentrated polyvinyl methyl ether solutions. Macromolecules, 22 (1989), 3409-3418. 

N. Nemoto, T. Kojima, T. Inoue, et al. Self-diffusion and tracer-diffusion coefficient and viscosity of concentrated solutions of linear polystyrenes in dibutyl phthalate. 

Values of/ not presented in Table III include those of Pefferkorn and Varoqui [59] from tracer diffusion for a maleic acid copolymer and of Bourdais [60] from conductance and electrophoresis (the latter to get Ap) for polyacrylate both sets of data agree well with the limiting law. In contrast to the entries in Table III from Reference [56], Dolar et al. [61] and Baumgartner et al [62] found values of / for polystyrene-sulfonate which are significantly higher than those predicted by the limiting law. 

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