Theory of dynamic scattering from ternary mixtures of two homopolymers and a solvent

Static and dynamic behavior of semidilute polymer solutions

“…The phenomenon of cluster (or domain) formation, which is still poorly understood, appears to be ubiquitous, occurring in both aqueous and non-aqueous solvents and apparently being independent of solvent qualit)a The two diffusive modes (collective and translational) become observable in the DLS experiment as a consequence of the size polydispersity in the system [86]. Benmouna et al [87] have shown that in a bidisperse system the signal from one species will be modulated by that from the second, leading to a bimodal auto- correlation function. The two relaxational modes correspond, respectively, to collective diffusion of the semidilute major component (De) and the interdiffusion coefficient (D~) of the minor component.…”

Neutron Spin Echo Investigations on the Segmental Dynamics of Polymers in Melts, Networks and Solutions

“…Using the random phase approximation (RPA), the coherent scattering intensity I (Q, t) of a polymer blend/solvent or a diblock copolymer/solvent system can be written as [169,170] I (Q, t)"A ! e !…”

Light Scattering from Mixtures of Two Polystyrenes in Toluene and Self-Diffusion Coefficients

“…The diffusivity matrix D C (q) can, however, be diagonalized to yield two eigenvalues, labeled as D C and D I . Using the eigenvalues and eigenvectors of the D C (q) matrix, we obtain for each of the dynamic matrix elements, S ij (q,t) as 11 Here the expressions for the eigenvalues D I and D C are given by where D av ) (D 11 + D 22 )/2 and ∆(D) ) D 11 D 22 -D 12 D 21 . The amplitudes A I ij and A C ij are given by A I 22 , A C 22 , A I 12 , and A C 12 can be obtained from the above equations by interchanging indices 1 with 2.…”

“…With the availability of X and Y, one can then calculate D 11 and D 22 from the experimental values of D C and D I using eqs 17 and 18. From the determined D 11 and D 22 , one can further calculate the amplitude ratio by using eq 19. Comparison of the calculated ratio with the experimental one would provide a consistency test of the experimental result and theory, provided that the amplitude ratio is accurately measured.…”