Tracer diffusion properties of core–shell latex films studied by photoinduced grating relaxation

Abstract

Shown are the tracer diffusion coefficients in the slow and the fast state, D s and D f , respectively, as well as the corresponding root mean squared displacements, M s and M f . Also included are the residence probabilities in the slow state, p s . Errors were estimated by varying the starting values of the parameters and then accepting fits up to a chi-square criterion chosen by visual inspection of the fit quality. Note that as the values of the fit parameters turned out to be correlated, the error in ratios D f /D s and M f /M s were comparable to those of the errors of the fit parameters.

Experimental investigation of anomalous molecular probe diffusion in entangled polymer melts

“…It is important to note that the quality of the fits to the photo-detector voltage for grating periods Λ near the jump were qualitatively similar to those shown in Figure 6. Deviations from τ D ∝ Λ 2 have been reported for diffusion in latex films, 22,23,25 which is expected given the heterogeneous nature of these systems. Similar results have also been obtained for the diffusion of nanoparticles in agarose solutions.…”

“…6. Deviations from τ D ∝ Λ 2 have been reported for diffusion in latex films, 22,23,25 which is expected given the heterogeneous nature of these systems. Similar results have also been obtained for the diffusion of nanoparticles in agarose solutions.…”

“…19 Hence, the reading beam is not absorbed by the sample so that no photo-induced isomerism occurs and the concentration of the AB540 isomers evolves as a result of diffusion alone. 20–23,25…”

“…19 Hence, the reading beam is not absorbed by the sample so that no photo-induced isomerism occurs and the concentration of the AB540 isomers evolves as a result of diffusion alone. [20][21][22][23]25 Our experiments satisfy the thick grating criterion: 19 d/L c 1, and we consider first-order Bragg diffraction with the reading beam passing through the grating at angle f/2 = l HeNe /2L (see Fig. 5).…”

“…These techniques include fluorescence correlation spectroscopy (FCS), 9,[13][14][15] photon correlation spectroscopy (PCS), 16 fluorescence recovery after photo bleaching (FRAP), 17,18 and forced Rayleigh scattering (FRS). [19][20][21][22][23][24][25] Each of these techniques have their (dis)advantages, and typically the length scale for the diffusion measurements is varied by less than a factor of 10.…”