Oligomer/Polymer Blend Phase Diagram and Surface Concentration Profiles for Squalane/Polybutadiene: Experimental Measurements and Predictions from SAFT-γ Mie and Molecular Dynamics Simulations

Abstract

The compatibility and surface behavior of squalane–polybutadiene mixtures are studied by experimental cloud point and neutron reflectivity measurements, statistical associating fluid theory (SAFT), and molecular dynamics (MD) simulations. A SAFT-γ Mie model is shown to be successful in capturing the cloud point curves of squalane–polybutadiene and squalane–cis-polybutadiene binary mixtures, and the same SAFT-γ Mie model is used to develop a thermodynamically consistent top-down coarse-grained force field to describe squalane–polybutadiene. Coarse-grained molecular dynamics simulations are performed to study surface behavior for different concentrations of squalane, with the system exhibiting surface enrichment and a wetting transition. Simulated surface profiles are compared with those obtained by fitting to neutron reflectivity data obtained from thin films composed of deuterated squalane (d-sq)–polybutadiene. The presented top-down parametrization methodology is a fast and thermodynamically reliable approach for predicting properties of oligomer–polymer mixtures, which can be challenging for either theory or MD simulations alone.

Coarse-grained molecular dynamics study of the self-assembly of polyphilic bolaamphiphiles using the SAFT-γ Mie force field

“…In this work, an alkyl substituted 4,4″-bis(2,3dihydroxypropoxy-p-terphenyl) molecule is coarse-grained (Fig. 1(Bottom)) following the strategies employed for other complex molecules such as surfactants, 53 asphaltenes, 54 polymers [55][56][57][58] and liquid crystals. 59 We choose to construct a molecular model by stitching together "building blocks" of smaller well-defined molecules for which there exists experimental thermophysical data, which allows the top-down parametrisation of the force fields.…”

Coarse‐Grained Molecular Simulation of Polymers Supported by the Use of the SAFT‐γ$\gamma$ Mie Equation of State

“…Most recently, polybutadiene/squalene mixtures have also been studied using SAFT-𝛾 Mie. [93] In a different approach, Walker et al [94,95] used the SAFT-𝛾 EoS to model polyvinyl alcohols copolymers, by rescaling the parameters obtained from the EoS to model fused-sphere models of polymers. Although this is useful in obtaining the correct structural properties, this rescaling of the parameters means that further simulations are required to find optimal but different force field parameters that produce the same thermodynamic properties as the EoS.…”

Simulation of Binodal and Spinodal Curves of Phase State Diagrams for Binary Polymer Systems

“…The first-theoretical simulation-concerns the statistical thermodynamics of solutions and polymer blends. These are the classical Flory-Huggins theory, the new Flory theory, the Sanchez-Lacombe theory, and Prigogine-Paterson theory [1][2][3][4][5], the statistical associating fluid theory (SAFT) [7], the polymer reference interaction site model (PRISM) [8], and the lattice cluster theory (LCT) [9]. Recently, the adapted mean field theory [10], the hybrid molecular dynamics-Monte Carlo method [11], the self-consistent field theory (SCFT) [12], and theoretically informed Langevin dynamics [13] have been used in diagram simulation.…”