Light scattering from concentrated solutions

For the Flory-Huggins theory, tire solution structure factor is given by 

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Angular dependence of light scattered from concentrated solutions of the bovine enzyme is characteristic of scattering from a rod-shaped polymer (58,102). Studies of the small-angle X-ray diffraction (106) and viscosity (107) of enzyme solutions as a function of protein concentration have also shown that the enzyme aggregates to form linear polymers. 

Goebel KD, Berry GC, Tarmer DW (1978) Properties of cellulose acetate. 111. Light scattering from concentrated solutions and films. Tensile creep and desalination studies on films. Journal of polymer science polymer physics edition 17(6) 917 937. 

Alternatively, the property measured could be the intensity of light scattered from the solution. In this case (Section 3.2.2) it turns out that the measured value depends on the product of the weight concentration and molecular weight of the solute. That is... 

Hyde, A..)., 1972, Light scattering from moderately concentrated solutions, in Light scattering from polymer solutions, ed.. VI.B. Huglin (lx>ndon. New York) p. 385. 

Patterson, G. D., 1981, Light scattering from concentrated pol5Tner solutions and gels, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.) 22 709-713. 

Further work with application to large molecules or particles in solution was done by Smoluchowski (J), Einstein (4), Debye (5, 6) and Zimm (7). For many years now the measurement of the intensity of the light scattered from dilute solutions of macromolecules as a function of concentration, and scattering angle has provided much important information on the size, shape, and thermodynamic properties of these... 

Richtering, W.H., Burchard, W., Jahns, E., Finkehnann, H. Light scattering from aqueous solutions of a nonionic surfactant (i4Eg) in a wide concentration range. J. Phys. Chem. 1988, 92(21), 6032-6040. 

The scattered light intensity from a polymer solution arises from the fluctuations in both the solvent density and the polymer concentration. These fluctuations are considered as stable during the timescale of the measurement in the static mode of light scattering (for more details, see Evans (1972)). The light scattered from just the polymer (in excess of the light scattered from the pure solvent) is given by (Burchard, 1994)... 

Liquid solutions also scatter light by a similar mechanism. In the case of a solution, the scattering may be traced to two sources fluctuations in solvent density and fluctuations in solute concentration. The former are most easily handled empirically by subtracting a solvent blank correction from measurements of the intensity of light scattered from solutions. What we are concerned with in this section, then, is the remaining scattering, which is due to fluctuations in the solute concentration in the solution. 

The use of photon correlation spectroscopy to study the dynamics of concentration fluctuations in polymer solutions and gels is now well established. In bulk polymers near the glass transition there will be slowly relaxing fluctuations in density and optical anisotropy which can also be studied by this technique. In this article we review the development of the field of photon correlation spectroscopy from bulk polymers. The theory of dynamic light scattering from pure liquids is presented and applied to polymers. The important experimented considerations involved in the collection and analysis of this type of data are discussed. Most of the article focuses on the dynamics of fluctuations near the glass transition in polymers. All the published work in this area is reviewed and the results are critically discussed. The current state of the field is summarized and many suggestions for further work are presented. 

The value of the refractive index increment dh/dc is needed at infinite dilution, but there is little concentration dependence in the normal concentration range used for light scattering of polymer solutions. The required value can therefore be obtained from... 

FIG. 14 Dependence of the second virial coefficient on added-salt concentration. NaPSS in NaCl solutions. Results by light scattering from Ref. 41 ( ), Ref. 30 (A) and by osmometry from Ref. 41 (o). The dashed line shows calculation of the second virial coefficient by incorporating electrostatic excluded volume effects after Ref. 30. 

Tnterest in the investigation of macromolecular diffusion phenomena in both dilute and concentrated solutions has received recent stimulus with the development of techniques vhich can conveniently and accurately identify the dynamic characteristics of light scattered from fluctuations in solute concentration. In dilute solution, part of this activity stems from the fact that the limiting value of the translational diffusion... 

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