A novel method of determining the aggregation behavior of microemulsion droplets

The study proposes a novel method of obtaining the information of second virial coefficient of interactions between microemulsion droplets by microcalorimetry. By employing a high sensitivity isothermal titration microcalorimetry (ITC) to measure the dilution heat of microemulsions solution, the information of second virial coefficient of the interactions between the microemulsion droplets can be derived with the number density of microemulsion solution. The derivation is based on a hard-sphere interaction potential assumption. The variance of the derived second virial coefficients were verified by the percolation behavior of different reverse micelles solutions of dioctyl sulfosuccinate sodium salt (ATO) in decane with or without solutes. The well-correlated data between the percolation temperatures and the second virial coefficients between the droplets prove the feasibility of ITC dilution measurement as a tool for determining the behavior of the non-ideal collisions between microemulsion.