Phase behavior of lattice associating binary mixtures: a Monte Carlo study

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Materials Science

Background:

• Binary mixtures exhibit complex phase behavior influenced by molecular interactions.
• Molecular association, such as dimer formation, can critically affect mixture properties.
• Understanding these effects is crucial for designing materials with specific phase characteristics.

Purpose of the Study:

• To investigate the impact of molecular association on the phase diagrams of binary symmetric mixtures.
• To determine the role of association energy in driving demixing transitions.
• To explore the structural ordering of the condensed phase under varying association strengths.

Main Methods:

• Utilizing the lattice gas model to simulate binary symmetric mixtures.
• Analyzing phase diagrams as a function of association energy.
• Characterizing the order of the condensed phase at different temperatures.

Main Results:

• Increased molecular association energy leads to qualitative changes in phase diagrams.
• Demixing transitions are suppressed at higher association energies.
• The demixing transition can manifest as either first-order or continuous.
• High association energy promotes highly ordered structures in the condensed phase, even at elevated temperatures.

Conclusions:

• Molecular association is a key factor governing the phase behavior of binary mixtures.
• The strength of association energy dictates the occurrence and nature of demixing.
• Lattice gas models provide valuable insights into structure-property relationships in mixtures.