X-PressMatter Group' IHPP PAS

Soft  Matter  Blog

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Discover the secrets of Soft Matter with us!

30 maja 2024

Critical concentration in binary mixtures of limited miscibility.

This report presents the new method, fast & simple in use, to determine the coexistence curve (binodal) and the critical concentration. Notable is the experimental simplicity of the method: for the preliminary estimation it is enough to prepare two samples with different total concentrations or densities and observed relative volumes occupied by coexisting phases (or fractional meniscus heights) for two different temperatures. The method is illustrated basing on experimental studies in nitrobenzene – hexane mixtures of limited miscibility. Notable is the importance of this result for a variety of practical implementations, ranging from chemical physics to foods and pharmaceuticals technologies. Additionally, the manifestations of various stages of the critical opalescence, from dark-navy-blue to bluish and whitish, in the broad range of temperatures and concentrations, are shown and discussed.

In the authors' opinion, the method offers a simple, reliable, and ‘fast in applications’ experimental tool, solving problems emerging after the cancellation of the CM law of rectilinear diameter. A brief discussion of some hardly indicated aspects of the critical opalescence is also given.




* 1. Popularization of knowledge, especially regarding Soft Matter Physics and the impact of High Pressure 

* 2. Promoting achievements of young scientists  associated with the X-PressMatter IHPP PAS Laboratory

* 3. Promoting knowledge about personalities of the world of science

* 4. Supporting co-organization/ organization of the "Show Yourself in Science" Workshop & International Seminar on Soft Matter

This WEBSITE was created to realize the following, main  GOALS:

Soft Matter systems have common features, such as the dominance of elements or local structures on the mesoscale, combined with their relatively weak interactions, which turns out to be sufficient to obtain a tendency to self-organize with even a small change in parameters. This additionally leads to extraordinary sensitivity to even minor endogenous and exogenous factors, e.g., nanoparticles and pressure. In the case of the latter, relatively low pressures P~1 GPa, or even much lower ones, can lead to phases/states with exotic features, often persisting after decompression.

Worth stressing, that for "classical hard matter" systems, a pressure similar to that at the Earth's core (~300 GPa) is typically required, and the resulting "exotic" properties most often disappear upon decompression.

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