Structural and thermodynamics properties of pure phase alkanes, monoamides and alkane/monoamide mixtures with an ab initio based force-field model

TL;DR

This study develops a polarizable force-field model based on quantum chemical calculations to accurately simulate the structural and thermodynamic properties of pure alkanes, monoamides, and their mixtures, revealing aggregation phenomena and molecular organization.

Contribution

The paper introduces a new ab initio based force-field model capable of simulating complex alkane and monoamide systems with high accuracy, including mixture behaviors.

Findings

Force-field accurately reproduces liquid-phase properties of alkanes.

Aggregation and trimerization observed in monoamide/dodecane mixtures.

Structural analysis shows formation of dimers and trimers at different concentrations.

Abstract

A polarizable force-field (FF) model for short- and long-alkane chains and amide derivatives was constructed based solely on accurate quantum chemical (QC) calculations. First, the FF model accuracy was accessed by performing molecular dynamics (MD) simulations to calculate liquid-phase thermodynamic and structural properties for alkanes, for which experimental data are available. Second, The FF was then used to perform molecular dynamics simulations to calculate thermodynamic, structural and excess properties of monoamide/dodecane mixtures, namely DEHiBA/dodecane and DEHBA/dodecane. Aggregation phenomena appear for both types of mixtures and monoamide pure phases. A detailed structural analysis revealed, at small monoamide mole fraction the formation of dimers, while trimerization at larger monoamide concentrations and in their pure phases. Analysis of the relative orientation of the dimers have also been performed and showed a small difference for both phases.