Anomalous diffusion in aqueous solutions of gelatin

Dynamic-light-scattering experiments on semidilute aqueous solutions of gelatin indicate three relaxation processes: an exponential for times less than {~}50 {μ}sec followed by a power law at intermediate time and then a stretched exponential at long time. The characteristic time of the stretched exponential diverges as the system evolves to a gel. The latter two relaxations can be explained in terms of an anomalous diffusion mechanism where the mean-square displacement behaves as 〈R²〉{~}lnt at intermediate time and 〈R²〉{~}t^β with {β}1 at late time. Length scales derivable from these diffusion mechanisms obey scaling, and it is proposed that {β} is related to the fracton density-of-states exponent and the fractal dimension of the gelatin molecules.