Thermal Stability and Phase Composition of Stratifying Polymer Solutions in Small-Volume Droplets

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“…Modeling of such small systems requires using some other approaches (see [31], for example). Note that despite the fact the term "nanoscale effects" is widely used, there is a broad class of systems, especially polymeric ones, with great molecular volumes and masses, in which such effects manifest themselves at characteristic sizes even several thousand times higher [20,26] (and such effects should probably be called "small-amounts-of-matter effects"). In addition to this, high surface-to-volume ratios can be obtained not only in nanoparticle materials but also in mesoporous ones while the morphology of pores also influences the characteristics of phase transitions including the magnetic ones [32].…”

“…The similar effects in systems with another nature of phase transitions (e.g. nanoparticles of stratifying solid solutions, stratifying liquid solutions in small-volume droplets and pores) can also be described using a model which is quite different in mathematical formulations but shares the same thermodynamical basis (see [17,20,26] for details).…”

“…The calculations have shown that, unlike bulk alloys, where a variation of the chemical composition of the system leads to changes in the volume fraction of co-existing phases (according to the lever rule) but does not affect the mutual solubility of components, in small-volume systems the chemical composition of the system determines not only the volume fractions of the phases, but also their equilibrium composition. Also, the calculations have shown an unusual effect of the significant variation of all phase equilibria characteristics depending on mutual position of co-existing solid and liquid phases in the structure [8,16,19,20,23] while all the sets of characteristics dramatically differ from each other and from the corresponding values for the bulk state. The shape of the system can also be taken into account using different approaches.…”

“…The compositions of co-existing phases and phase transition temperatures in nanoscale systems (nanoparticles, nanodroplets etc.) depend on the size of the system [13][14][15][16][17][18][19][20][21][22][23], its shape [16][17][18][19]22] as well as on the thermodynamical properties of all interfaces [23]. In phase diagrams, the mentioned effects can manifest themselves as significant shifts of characteristic points, shifts and deformations of characteristic lines in comparison with phase diagrams for the bulk-state systems.…”

“…In order to calculate the phase equilibria at the nanoscale by thermodynamical methods, it is necessary to minimize the total Gibbs function of the system with allowance for the contribution of all interfaces and to analyze the configuration of its minima (see [16,20,21], for example). Despite the fact that there is a set of papers observing the mentioned effects, the general regularities cannot be obtained from most of them at present due to the substantial differences in the models derived and some critical gaps.…”