Transition from thermodynamically stable solution to colloid dispersion state

Abstract

In this work, we investigated the transition between solution and dispersion state of the poly-N-isopropylacrylamide microgel latex. The aggregation state of the colloid system was described by applying the multiple chemical equilibrium model. The model predicts that in the case of ordinary colloid dispersions, formation of small equilibrium aggregates cannot be expected in the practically accessible concentration range. However, when the particle–particle attraction is small enough, then formation of finite size aggregates in equilibrium with the monomers may take place. To test the model, the aggregation behavior of a temperature-sensitive soft colloid dispersion (poly-N-isopropylacrylamide microgels) was investigated for which the attractive interactions could be precisely controlled by the temperature of the system. The experimental results provide a support for the theoretical predictions.