Formation of dissipative structures in microscopic models of mixtures with species interconversion

Abstract

The separation of substances into different phases is ubiquitous in nature and important scientifically and technologically. This phenomenon may become drastically different if the species involved, whether molecules or supramolecular assemblies, interconvert. In the presence of an external force large enough to overcome energetic differences between the interconvertible species (forced interconversion), the two alternative species will be present in equal amounts, and the striking phenomenon of steady-state, restricted phase separation into mesoscales is observed. Such microphase separation is one of the simplest examples of dissipative structures in condensed matter. In this work, we investigate the formation of such mesoscale steady-state structures through Monte Carlo and molecular dynamics simulations of three physically distinct microscopic models of binary mixtures that exhibit both equilibrium (natural) interconversion and a nonequilibrium source of forced interconversion. We show that this source can be introduced through an internal imbalance of intermolecular forces or an external flux of energy that promotes molecular interconversion, possible manifestations of which could include the internal nonequilibrium environment of living cells or a flux of photons. The main trends and observations from the simulations are well captured by a nonequilibrium thermodynamic theory of phase transitions affected by interconversion. We show how a nonequilibrium bicontinuous microemulsion or a spatially modulated state may be generated depending on the interplay between diffusion, natural interconversion, and forced interconversion.

A systematic study on immiscible binary systems undergoing thermal/photo reversible chemical reactions

“…Recently, some researchers introduced a third way by combining the ideal term and the chemical affinity modified term and they observed complicated phase behaviors. 21–23 This finding indicates that this simple system might have more phenomena to be discovered and it, thus, deserves a thorough study.…”

Tribute to Pablo G. Debenedetti

“…These techniques have also been applied to investigate freezing near water–vapor interfaces, which is critical to understanding ice nucleation at atmospherically relevant conditions . Along with Frank Stillinger, Pablo has developed models to study chiral symmetry breaking, − the process by which one enantiomer becomes preferentially favored over its mirror image. Enantiomeric preference is ubiquitous in biological systems: the 19 naturally occurring proteinogenic chiral amino acids are l -enantiomers, whereas natural sugars are typically found in their d -form.…”

“…Enantiomeric preference is ubiquitous in biological systems: the 19 naturally occurring proteinogenic chiral amino acids are l -enantiomers, whereas natural sugars are typically found in their d -form. The models stemming from this highly productive collaboration have provided new insights into the mechanism underpinning this process as well as its broader consequences on solid–fluid and fluid–fluid , phase behavior, crystal attrition, and self-assembly phenomena . They are also helpful in identifying and analyzing possible mechanisms underlying the origin of biological homochirality.…”

Regioselective synthesis of 4-arylamino-1,2-naphthoquinones in eutectogel as a confined reaction medium using LED light

“…Supramolecular assembly is a ubiquitous phenomenon in nature in which molecules spontaneously form aggregates via non-covalent interactions, which are intrinsically able to control selectivity, rate of conversion and kinetics of chemical processes in biological systems. 1 It is surprising to see the existence of life facilitated by the synthesis of specific organic molecules in confined reaction environments such as reactive pockets, bilayer or multilayer membranes, micelles, vesicles, emulsions, gels, helical tubules, polyelectrolyte nanoparticles, cells and fibrillar network structures in bottom-up assembly processes. 2 Many examples of highly precise and well-programmed natural assembly processes have been documented in science, technology and medicine, 3 the topic has emerged as a discrete field of investigation because of its potential to enhance organic synthesis under sustainable reaction conditions.…”