Poly mutual diffusion coefficient

Figure 5 The mutual diffusion coefficient, D, of sodium chloride as a function of reciprocal matrix hydration, H, in various methacrylate gels. HPMA-GMA polyfhydroxypro-pyl methacrylate-co-glyceryl methacrylate) HEMA polyfhydroxyethyl methacrylate) MMA-GMA poly(methyl methacrylate-co-glyceryl methacrylate) HEMA-MMA poly-(hydroxyethyl methacrylate-co-methyl methacrylate) HPMA-MMA polyfhydroxypropyl methacrylate-co-methyl methacrylate) HPMA-GDMA polyfhydroxypropyl methacry-late-co-glyceryl dimethacrylate). (From Ref. 64.)...

Mechanistic Ideas. The ordinary-extraordinary transition has also been observed in solutions of dinucleosomal DNA fragments (350 bp) by Schmitz and Lu (12.). Fast and slow relaxation times have been observed as functions of polymer concentration in solutions of single-stranded poly(adenylic acid) (13 14), but these experiments were conducted at relatively high salt and are interpreted as a transition between dilute and semidilute regimes. The ordinary-extraordinary transition has also been observed in low-salt solutions of poly(L-lysine) (15). and poly(styrene sulfonate) (16,17). In poly(L-lysine), which is the best-studied case, the transition is detected only by QLS, which measures the mutual diffusion coefficient. The tracer diffusion coefficient (12), electrical conductivity (12.) / electrophoretic mobility (18.20.21) and intrinsic viscosity (22) do not show the same profound change. It appears that the transition is a manifestation of collective particle dynamics mediated by long-range forces but the mechanistic details of the phenomenon are quite obscure. 

Figure 10. Mutual diffusion coefficients, of the two molecular populations of a fluorescent dye dispersed in poly(1-trimethyl-l-propyne) plotted as functions of reciprocal absolute temperature. The technique used was laser fluorescence photobleaching recovery.

Ohshima, A., Yamagata, A., Sato, T, and Teramoto, A., Entanglement effects in semiflexible polymer solutions 3. Zero-shear viscosity and mutual diffusion coefficient of poly(n-hexyl isocyanate) solutions. Macromolecules, 32, 8645-8654 (1999). 

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).

Figure 4.25. (a) The mutual diffusion coefficient in the miscible polymer blend poly(vinyl chloride)-polycaprolactone (PVC-PCL) at 91 °C, as measured by x-ray microanalysis in the scanning electron microscope (Jones et al. 1986). The solid line is a fit assuming that the mutual diffusion coefficient is given by equation (4.4.11), with the composition dependence of the tracer diffusion coefficient of the PCL given by a combination of equations (4.4.9) and (4.4.10). The tracer diffusion coefficient of the PVC is assumed to be small in comparison, (b) The calculated profile of diffusion between pure PVC and pure PCL, on the basis of the concentration dependence of the mutual diffusion coefficient shown in (a). The reduced length u — where the... 

For a binary system, D j is the binary mutual diffusion coefficient Dp. The FRRPP process, however, is essentially a ternary system of the polymer/monomer/ precipitant type (such as polystyrene/styrene/water or poly(methacrylic acid)/ methacrylic acid/water). Let us designate the polymer (poly(methacrylic acid) or polystyrene) as component 1 precipitant (such as water or ether) as component 2 and the monomer (methacrylic acid or polystyrene) as component 3. Therefore, for the FRRPP process, we have four mutual diffusivities in the mixture Dn is approximated as the mutual diffiisivity of the polymer and precipitant D22 is approximated as the mutual diffiisivity of the monomer and the precipitant D 2 is the mutual dif-fusivity for the mass transfer of the polymer due to composition gradient of the monomer and D21 is the mutual diffiisivity for the mass transfer of the monomer... 

The concentration dependence of D (c) in the concentrated regime depends on the solvent quality and the local viscosity. It is often observed to go through a maximum with concentration due to a large increase of local viscosity with concentration. However, if the polymer is well above its glass-transition temperature, the mutual-diffusion coefficient can even increase throughout the concentrated regime. Solutions of poly(dimethyl siloxane) in dioxane exhibit a continuously increasing mutual-diffusion coefficient. 

Figure 3.27. Mutual diffusion coefficient of poly(a-methyl styrene) in a theta solvent at different concentrations in the dilute regime. The molecular weight of the polymer is indicated adjacent to each plot. (From Ref. 31.)...

ATR-FTIR has been employed to determine the interdiffiision rate between polystyrene and poly(vinyl methyl ether) noted to be miscible by other techniques [296]. Spin coating of a thin PS film on an ATR germanium crystal, followed by spin coating a thin film of PVME (from a water solution) yielded thin film laminates, which were heated above the Tg of PS to determine the interdiffusion of the layers by ATR-FTIR. As interdiflusion occurred, the PVME band at 2820 cm increased and the PS bands at 2250 and 3030 cm decreased. At 5 °C above the Tg of PS, equilibrium was achieved in < 10 hours, and the results allowed for a calculation of the mutual diffusion coefficient. A similar study reported in a more recent study yielded mutual diffusion coefficients in the same range [297]. 

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,... 

In recognizing these benefits, a number of FTIR/ATR studies have been made. The diffusion of additives in polyolefins have been studied [67] through a measurement of their infrared absorbances as a function of mass uptake. Environmental penetrants have been studied [68], The mutual interdififusion of polymers has also been studied using the FTIR/ATR method [69]. The interpenetration of semicrystalline polymers such as poly (ether imide/poly(aryl ether ketone) has been examined [70]. The interdiffusion of polystyrene and poly(methyl ether) has also been studied and diffusion coefficients measured which agreed with other approaches [71]. 

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