Multifractal detrended fluctuation analysis of intensity time series of photons scattered by tracer particles within a polymeric gel

Some properties of spatial confinement of tracer colloidal particles within polyacrylamide dispersions are studied by means of the well-known dynamic light scattering (DLS) technique. DLS allows obtaining sequences of elapsed times of scattered photons. In this work, the aqueous polyacrylamide dispersion has no crosslinking and the volume fraction occupied by the tracer particles is 0.02 %. Our experimental setup provides two sequences of photons scattered by the same scattering volume that corresponds to two simultaneous experiments (Channel A and Channel B). By integration of these sequences, the intensity time series are obtained. We find that both channels are antipersistent with Hurst exponent, H∼0.43 and 0.36, respectively. The antipersistence of the intensity time series indicates a subdiffusive dynamics of the tracers in the polymeric network, which is in agreement with the time dependence of the tracer's mean square displacement.