Mixtures coil sizes

To obtain this result, Eq. (4.52) has been used for the critical composition of an A-B mixture and the ideal coil size is — b /N. For symmetric... 

The coil size in semidilute solution can also be determined using SANS, by utilizing a mixture of deuterium-labelled and unlabelled chains in an appropriate mixture of deuterium-labelled and unlabelled solvent with the same average contrast as the polymer mixture (contrast matched, -see Problem 5.26). If the fraction x of the chains are labelled, the q-... 

Phe search for new ways and opportunities is continuing in the framework of the third approximation of Flory-lluggins theory, with due account of fine effects of changes in the molecular coil sizes of one polymer with the concentration of the other i>olymer in the mixture. 

Of course, it is also possible to simulate colloid-polymer mixtures where the polymers are described as coarse-grained chain molecules with N beads (up to N=500 was chosen ), but this still implies coil sizes of a few nanometers (and the colloid sizes of interest are in the same range), far from the sizes in the micrometer range which are of experimental interest. ... 

Schmitt, Kirste, and Jelenic utilized neutron scattering to determine the coil sizes and the second virial coefficients with mixtures containing two styrene/acrylonitrile copolymers, one of which was deuterated. The interaction parameter calculated... 

Both positive and negative deviations from the linear additive line have been observed in drag reduction caused by polymer/polymer mixtures depending upon their composition, flow rate, and polymer species. The maximum synergism is obtained at a specifle composition. The random coil size, rigidity, and salvation of polymer molecules appear to be responsible for the synergism in drag reduction by polymer/polymer mixtures (169). 

Mixed solvents are generally unsatisfactory for use in the determination of polymer molecular weights owing to the likelihood of selective absorption of one of the solvent components by the polymer coil. The excess of polarizabilit f of the polymer particle (polymer plus occluded solvent) is not then equal to the difference between the polarizabilities of the polymer and the solvent mixture. For this reason the refractive increment dn/dc which would be required for calculation of K, or of i7, cannot be assumed to equal the observed change in refractive index of the medium as a whole when polymer is added to it, unless the refractive indexes of the solvent components happen to be the same. The size Vmay, however, be measured in a mixed solvent, since only the dissymmetry ratio is required for this purpose. 

Homostranded coiled coils at a final concentration of 50 mM were incubated in 100 mM potassium phosphate buffer (pH 7.0), containing 200 mM KC1 and 1 mM EDTA, with 100 mM GSH and 100 mM GSSH (GSSH was prepared by air oxidation of GSH and purified). The mixture was stirred under N2 in a gas-tight vial at rt. Samples of the mixture were analyzed by RP-HPLC [column Zorbax SB-C8 (4.6 mm x 25 cm, 5-pm particle size, 300-A pore size) linear AB gradient (2% B-min ) solvents A =0.05% aq TFA, B = 0.05% TFA in MeCN flow rate=lmL-min-1]. 

---