Long-Range Surface-Directed Polymerization-Induced Phase Separation: A Computational Study

Abstract

The presence of a surface preferably attracting one component of a polymer mixture by the long-range van der Waals surface potential while the mixture undergoes phase separation by spinodal decomposition is called long-range surface-directed spinodal decomposition (SDSD). The morphology achieved under SDSD is an enrichment layer(s) close to the wall surface and a droplet-type structure in the bulk. In the current study of the long-range surface-directed polymerization-induced phase separation, the surface-directed spinodal decomposition of a monomer–solvent mixture undergoing self-condensation polymerization was theoretically simulated. The nonlinear Cahn–Hilliard and Flory–Huggins free energy theories were applied to investigate the phase separation phenomenon. The long-range surface potential led to the formation of a wetting layer on the surface. The thickness of the wetting layer was found proportional to time t*1/5 and surface potential parameter h11/5. A larger diffusion coefficient led to the formation of smaller droplets in the bulk and a thinner depletion layer, while it did not affect the thickness of the enrichment layer close to the wall. A temperature gradient imposed in the same direction of long-range surface potential led to the formation of a stripe morphology near the wall, while imposing it in the opposite direction of surface potential led to the formation of large particles at the high-temperature side, the opposite side of the interacting wall.

State-of-the-art review of porous polymer membrane formation characterization—How numerical and experimental approaches dovetail to drive innovation

“…The dynamic interplay of these phenomena is described by an array of system properties and process parameters that in sum determine the final membrane morphology. It follows that membrane appearance and properties Wetting effect (Goyal et al, 2021) Effect of viscoelasticity (Yoshimoto and Taniguchi, 2021) Gelation where the liquid transforms into solid-like structure Cummings et al, 2018;Hopp-Hirschler and Nieken, 2018;Cervellere et al, 2019Cervellere et al, , 2021Garcia et al, 2020;Padilha Júnior et al, 2020;Ronsin et al, 2020;Ghaffari et al, 2021;Goyal et al, 2021;Rabani et al, 2021;Yoshimoto and Taniguchi, 2021;Zhang et al, 2021Zhang et al, , 2022 Coarse Heyes, 2007;Ahmed and Sadus, 2009;Hyon and Liu, 2010;Barrett and Süli, 2011;Semiromi and Azimian, 2011;Morthomas et al, 2017;Geada et al, 2018;Zhou et al, 2020;Tang and Müller, 2021 Stochastic simulation [e.g., Monte Carlo (MC) method]…”

“…The spatiotemporal scale of mesoscopic phase-field models is sufficient to depict the microstructure evolution of a membrane, which can be formed via TIPS (Lee K.-W. D. et al, 2004;Tegze et al, 2005;Saylor et al, 2007;Zhang et al, 2008;Asai et al, 2009;Li et al, 2012;Mino et al, 2015;Hou et al, 2016;Zhu et al, 2016;Cervellere et al, 2019), EIPS (Dayal and Kyu, 2006;Buxton and Clarke, 2007;Wodo and Ganapathysubramanian, 2014;Zoumpouli and Yiantsios, 2016;Cummings et al, 2018;Negi et al, 2018;Rabani et al, 2021;Tang and Müller, 2021), NIPS/VIPS (Wodo and Ganapathysubramanian, 2012;Sun et al, 2017;Hopp-Hirschler and Nieken, 2018;Tree et al, 2018Tree et al, , 2019Garcia et al, 2020;Padilha Júnior et al, 2020;Cervellere et al, 2021;Fang et al, 2021; Zhang et al, 2021), and polymerization induced phase separation (PIPS) (Kim and Palffy-Muhoray, 1993;Chan and Rey, 1997;Rey, 2000, 2001;Lee et al, 2003;Higuchi et al, 2013;Ghaffari et al, 2019Ghaffari et al, , 2021Dong et al, 2021).…”

“…The phase separation occurs once the liquid mixture is inside the spinodal region for a sufficiently large degree of polymerization. Phase-field modeling about polymerization induced membrane structure can be found in Kim and Palffy-Muhoray (1993), Chan and Rey (1997), Rey (2000, 2001), Lee et al (2003), Higuchi et al (2013), Ghaffari et al (2019Ghaffari et al ( , 2021, and Dong et al (2021).…”

The Effect of Conductive Heat Transfer on the Morphology Formation in Polymer Solutions Undergoing Thermally Induced Phase Separation

“…The model that was employed to describe the thermodynamics of phase separation through spinodal decomposition was the Flory-Huggins theory, which is capable of describing the thermodynamics of phase separation in polymer solutions very successfully [ 16 ]. Although Flory-Hugging’s theory has some limitations, it is a very effective theory in the phase equilibrium investigations [ 1 , 6 , 8 , 15 , 20 , 44 ]. The free energy of mixing of the homogenous system in the Flory-Huggins theory is defined as [ 64 ]: where T is the temperature, v is the volume of the cell or segment of the polymer, is Flory’s interaction parameter, k B is the Boltzmann’s constant, N 1 and N 2 are the degrees of polymerization of the solvent and the polymer, respectively.…”

“…Producing anisotropic morphologies is one of the most prominent features of the TIPS process [ 36 , 37 , 38 , 39 , 40 , 41 ]. An electrical field, a temperature gradient, a shear flow, a chemical reaction, or a concentration gradient can all be employed to create anisotropy [ 2 , 17 , 18 , 42 , 43 , 44 ]. A deep understanding of the impact of these techniques to induce anisotropy leads to in-depth knowledge of the fabrication of functional polymeric materials with desired morphologies, and mechanical, optical, and thermal properties [ 2 , 6 , 45 , 46 , 47 , 48 ].…”