A computational study of the Ludwig-Soret effect on the thermal-induced phase separation process in polymer solutions

Thermal-induced phase separation (TIPS) is one of the methods used to fabricate functional polymeric materials, i.e. PDLC films for electro-optical devices such flat-panel displays, switchable windows etc., and microporous synthetic membranes from polymer solutions. Since the characteristic thermal, mechanical, and optical properties of these materials are controlled by the morphological features, it it important to understand the phase separation mechanism that forms these materials. In this work, the effect of thermal diffusion, also known as the Ludwig-Soret effect, on the TIPS method of phase separation via the SD mechanism in polymer solutions under non-uniform temperature field has been investigated using the computational technique. The Ludwig-Soret effect occurs when a temperature gradient applied to a fluid mixture induces a net mass flow, which leads to the formation of a concentration gradient. A rigorous mathematical model for TIPS via the spinodal decomposition mechanism based on the nonlinear Cahn-Hilliard and Flory-Huggins theories combined with thermal diffusion phenomenon has been formulated for binary polymer solutions under non-uniform temperature field and solved numerically. Numerical simulation results revealed that the thermal diffusion phenomenon had very little or negligible effect on the phase separation mechanism under a non-uniform temperature field, which was reflected from the studies of the time evolution of structure factor and transition time from the early to the intermediate stages of SD.

A computational study of the Ludwig-Soret effect on the thermal-induced phase separation process in polymer solutions

Thermal-induced phase separation (TIPS) is one of the methods used to fabricate functional polymeric materials, i.e. PDLC films for electro-optical devices such flat-panel displays, switchable windows etc., and microporous synthetic membranes from polymer solutions. Since the characteristic thermal, mechanical, and optical properties of these materials are controlled by the morphological features, it it important to understand the phase separation mechanism that forms these materials. In this work, the effect of thermal diffusion, also known as the Ludwig-Soret effect, on the TIPS method of phase separation via the SD mechanism in polymer solutions under non-uniform temperature field has been investigated using the computational technique. The Ludwig-Soret effect occurs when a temperature gradient applied to a fluid mixture induces a net mass flow, which leads to the formation of a concentration gradient. A rigorous mathematical model for TIPS via the spinodal decomposition mechanism based on the nonlinear Cahn-Hilliard and Flory-Huggins theories combined with thermal diffusion phenomenon has been formulated for binary polymer solutions under non-uniform temperature field and solved numerically. Numerical simulation results revealed that the thermal diffusion phenomenon had very little or negligible effect on the phase separation mechanism under a non-uniform temperature field, which was reflected from the studies of the time evolution of structure factor and transition time from the early to the intermediate stages of SD.

Degradable ultrathin high-performance photocatalytic hydrogen generator from porous electrospun composite fiber membrane with enhanced light absorption ability

Poly(L-lactide) (PLA)/TiO2/Pt composite fiber membrane with internal porous channel structure is fabricated by skillfully tuning the breath figure mechanism and vapor induced phase separation mechanism with solute and solvent matching...

Assessment of the UCST-type liquid-liquid phase separation mechanism of imidazolium-based ionic liquid, [C8mim][TFSI], and 1,4-dioxane by SANS, NMR, IR, and MD simulations

Liquid–liquid phase separation of binary systems for imidazolium-based ionic liquids (ILs), 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Cnmim][TFSI], n represents the alkyl chain length of the cation) with 1,4-dioxane (1,4-DIO) has been observed as...

Phase Separation Mechanism for a Unified Understanding of Dissipative Pattern Formation in a Liesegang System

Dissipative patterns with solid-phase transitions are ubiquitous in nature. Despite their ubiquitous nature, there is no unified understanding of the non-equilibrium self-assembly mechanisms of such pattern formation. The Liesegang pattern...

Polymerization induced phase separation as a generalized methodology for multi-layered hydrogel tubes

Herein, we report a conceptually chemical strategy to facilitate the fabrication of layered hydrogel tubes based on the polymerization-induced phase separation mechanism.