Gibbs–Duhem Relation for Phase-Field Models of Polymeric Mixtures

Alhasan, Rami; Tree, Douglas R.

doi:10.1021/acs.macromol.1c02021

Cited by 2 publications

(1 citation statement)

References 30 publications

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“…For a fluid with K components, the chemical potential has K − 1 independent variables because of the constraint for the volume concentration K j=1 φ j = 1 due to incompressibility. Most importantly, for multicomponent fluids, the chemical potentials are constrained by the Gibbs-Duhem relation (Alhasan & Tree 2022), which leads to a thermodynamically consistent mobility consistent with the Onsager theorem (Balluffi, Allen & Carter 2005), as is demonstrated in the current work. This is in contrast to the case of constant mobility (Kim 2007;Boyer et al 2010).…”

Section: Introductionsupporting

confidence: 65%

A thermodynamically consistent diffuse interface model for the wetting phenomenon of miscible and immiscible ternary fluids

Wang,

Zhang,

et al. 2023

J. Fluid Mech.

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The wetting effect has attracted great scientific interest because of its natural significance as well as technical applications. Previous models mostly focus on one-component fluids or binary immiscible liquid mixtures. Modelling of the wetting phenomenon for multicomponent and multiphase fluids is a knotty issue. In this work, we present a thermodynamically consistent diffuse interface model to describe the wetting effect for ternary fluids, as an extension of Cahn's theory for binary fluids. In particular, we consider both immiscible and miscible ternary fluids. For miscible fluids, we validate the equilibrium contact angle and the thermodynamic pressure with Young's law and the Young–Laplace equation, respectively. Distinct flow patterns for dynamic wetting are presented when the surface tension and the viscous force dominate the wetting effect. For immiscible ternary fluids, we manipulate the wettability of two contact droplets deposited on a solid substrate according to three scenarios: (I) both droplets are hydrophilic; (II) a hydrophilic droplet in contact with a hydrophobic one; (III) both droplets are hydrophobic. The contact angles at each triple junction from the simulations are compared with Young's contact angle and Neumann's triangle rule. Simulations for the validation of our work are performed in two and three dimensions. In addition, we model the evaporation process of a ternary droplet and obtain the same power law as that of previous experiments. Our model allows one to relate the interfacial energies with surface composition, enabling the modelling of the coffee-ring phenomenon in further perspective.

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Section: Introductionsupporting

confidence: 65%

A thermodynamically consistent diffuse interface model for the wetting phenomenon of miscible and immiscible ternary fluids

Wang,

Zhang,

et al. 2023

J. Fluid Mech.

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Nonsolvent-induced phase separation inside liquid droplets

Alhasan

Banks

et al. 2023

The Journal of Chemical Physics

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Nonsolvent-induced phase separation (NIPS) is a popular method for creating polymeric particles with internal microstructure, but many fundamental questions remain surrounding the kinetics of the complex coupled mass transfer and phase separation processes. In this work, we use simulations of a phase-field model to examine how (i) finite domain boundaries of a polymer droplet and (ii) solvent/nonsolvent miscibility affect the NIPS process. To isolate the effects of phase separation kinetics and solvent/nonsolvent mass transfer on the NIPS process, we study two different cases. First, we investigate droplet concentrations that originate inside the two-phase region, where phase separation kinetics alone governs the microstructure. Second, we investigate the effects of solvent/nonsolvent mass transfer by studying droplet concentrations that begin outside the two-phase region, where both phase separation kinetics and mass transfer play a role. In both cases, we find that qualitative NIPS behavior is a strong function of the relative location of the initial droplet composition with respect to the phase diagram. We also find that polymer/nonsolvent miscibility competes with solvent/nonsolvent miscibility in driving NIPS kinetic behavior. Finally, we examine polymer droplets undergoing solvent/nonsolvent exchange and find that the model predicts droplets that shrink with nearly Fickian diffusion kinetics. We conclude with a brief perspective on the state of simulations of NIPS processes and some recommendations for future work.

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Gibbs–Duhem Relation for Phase-Field Models of Polymeric Mixtures

Cited by 2 publications

References 30 publications

A thermodynamically consistent diffuse interface model for the wetting phenomenon of miscible and immiscible ternary fluids

A thermodynamically consistent diffuse interface model for the wetting phenomenon of miscible and immiscible ternary fluids

Nonsolvent-induced phase separation inside liquid droplets

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