Crossover criticality in complex fluids

摘要

If the structure of a complex fluid is characterized by a nanoscopic or mesoscopic length scale comparable with the correlation length of critical fluctuations, a specific sharp crossover from classical mean-field behaviour to Ising asymptotic behaviour is observed. In the region far away From the critical point where the correlation length is still smaller than this structural length scale, one can observe mean-field behaviour. Ultimately, in the nearest vicinity of the critical point, the correlation length becomes dominant and one should expect Ising singular behaviour. Such a crossover is observed in polymer solutions, where the structural length scale is controlled by the molecular weight of polymer, and in aqueous salt solutions, where the range of Ising behaviour can be tuned by the salt concentration. The structural length diverges at a tricritical point. Crossover to mean-field tricriticality can be naturally incorporated into a universal scaling description of polymer solutions. [References: 41]