Modeling the Phase Equilibria of Associating Polymers in Porous Media with Respect to Chromatographic Applications

Abstract

Associating copolymers self-assemble during their passage through a liquid chromatography (LC) column, and the elution differs from that of common non-associating polymers. This computational study aims at elucidating the mechanism of their unique and intricate chromatographic behavior. We focused on amphiphilic diblock copolymers in selective solvents, performed the Monte Carlo (MC) simulations of their partitioning between a bulk solvent (mobile phase) and a cylindrical pore (stationary phase), and investigated the concentration dependences of the partition coefficient and of other functions describing the phase behavior. The observed abruptly changing concentration dependences of the effective partition coefficient demonstrate the significant impact of the association of copolymers with their partitioning between the two phases. The performed simulations reveal the intricate interplay of the entropy-driven and the enthalpy-driven processes, elucidate at the molecular level how the self-assembly affects the chromatographic behavior, and provide useful hints for the analysis of experimental elution curves of associating polymers.

Static and dynamic adsorption of supramolecular surfactant for oil recovery in high temperature and salinity conditions

“…(2) sodium 3-hydroxydodecane-1-sulfonate (1 and 2 in the commercial product STEPANTAN ® AS-12 46, produced by Stepan ® Company, Matamoros, Tamaulipas, México), and (3) 3-[(3-dodecanoylamidopropyl)dimethylazaniumyl]-2-hydroxypropane-1-sulfonate (AMPHOSOL ® CS-50, also produced by Stepan ® , México) (Skoreyko et al, 2011;Wang et al, 2022).…”

“…The supramolecular surfactant was characterized following the procedure previously reported (Akhlaghi & Riahi, 2019;Skoreyko et al, 2011;Wang et al, 2022).…”

“…The critical micelle concentration (CMC) was determined by HPLC at 30 C in seawater and connate water (Wang et al, 2022). A stock solution of supramolecular surfactant at 5000 ppm in seawater and connate water was prepared.…”

“…where c 0 is the surfactant initial concentration, c eq is the surfactant concentration after adsorption, V is the volume of the surfactant solution (mL), and m is the initial mass of rock (g) (Akhlaghi & Riahi, 2019;Nieto-Alvarez et al, 2014;Rosen, 2004;Sammalkorpi et al, 2009;Wang et al, 2022).…”

“…Under dynamic conditions, the surface saturation occurred at 1488 ppm. Therefore, 2000 ppm was selected as the surfactant concentration for evaluation the oil recovery factor (ORF) to assess the wettability alteration and additional properties of the ORF with respect to the multifunctional properties previously described (Wang et al, 2022). Figure 8 depicts the supramolecular surfactant capacity of wettability alteration.…”