Effect of prenucleation clusters arising from liquid-liquid phase transition on nucleation in a one-component charged colloidal suspension

It is generally thought that liquid-liquid phase transition (LLPT) in a one-component suspension never or only very rarely happens. If this were true, it would contradict the two nonclassical nucleation models building on either liquid droplets or prenucleation clusters (PNCs). One way out of this paradox is to suppose that LLPT occurs in pathway to nucleation. This study specifies the physical parameters of charged colloids which can bring out LLPT according to the consistent prediction of the DLVO (Derjaguin-LandauVerwey-Overbeek) potential and the Sogami potential about long-range attraction, and reveals that surface charge is not the only factor to affect attraction, size also plays an essential role. For the first time, we follow exactly the evolution from LLPT to nucleation in which PNCs participate, and characterize pre ordered liquid-like property of the PNCs and their particle-like and template effect by optical microscopy and light scattering. Furthermore, it is found that when the configuration of the PNCs is changed by a little salt, the pathway to nucleation is altered significantly. Our results demystify LLPT in a one-component suspension and dissolve the paradox, thus extending the range of applicability of the nonclassical nucleation models. (c) 2020 Elsevier Inc. All rights reserved.