Reentrant phase behavior of nanoparticle solutions probed by small-angle scattering

Publication date: Available online 27 February 2019Source: Current Opinion in Colloid & Interface ScienceAuthor(s): Sugam Kumar, Debes Ray, Sohrab Abbas, Debasish Saha, Vinod K. Aswal, Joachim KohlbrecherAbstractThe nanoparticles in solution represent a model system, where the well-established colloidal theories such as Debye-Hückel (DH) theory and/or DLVO theory can be implemented to predict the nanoparticle phase behavior. Recently, reentrant phase transitions in a wide range of colloids (e.g. inorganic and organic nanoparticles, polymers, and biomolecules) have been observed, which are not consistent with these theories. The colloids in the reentrant phase behavior undergo a phase change and return back to the original phase with respect to a specific physiochemical parameter (e.g. ionic strength, concentration of different additives, temperature etc.). The nanoparticle-polymer/multivalent-ions systems, demonstrating such phase transition and the corresponding phase behavior in terms of interparticle interactions have been probed by small-angle scattering. It has been shown how the tuning in interparticle interactions using external parameters can lead to reentrant phase behavior and utilize the nanoparticle aggregation for building nanohybrids. The deviations of the present observations from those of the standard colloidal theories and the anticipated challenges are also discussed.Graphical abstract

Source: Current Opinion in Colloid and Interface Science - February 27, 2019 Category: Chemistry Source Type: research