CO2 in Lyotropic Liquid Crystals: Phase Equilibria Behavior and Rheology

Abstract

The CO2 absorption of liquid crystalline phases of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic L92, (EO)8(PO)47(EO)8), monoethanolamine (MEA), and water, with a composition of 60% L92/10% MEA/30% water has been investigated to assess potential use in carbon capture and storage applications. Vapor–liquid equilibrium data of the liquid crystalline system with CO2 was recorded up to a CO2 partial pressure of 6 bar, where a loading of 38.6 g CO2/kg sample was obtained. Moreover, the phase transitions occurring during the loading process were investigated by small angle X-ray scattering (SAXS), presenting a transition from lamellar + hexagonal phase to hexagonal (at 25 °C). In addition, the rheology of samples with varying loadings was also studied, showing that the viscosity increases with increasing CO2-loading until the phase transition to hexagonal phase is completed. Finally, thermal stability experiments were performed, and revealed that L92 does not contribute to MEA degradation.

Glucose-induced self-assembly and phase separation in hydrophilic triblock copolymers and the governing mechanism

“…In addition to such unimers in the dilute concentration regime, reported studies have also shown BCPs to display rich phase behaviour, forming different lyotropic liquid crystalline regions in the high concentration regime (425 %w/v) that are highly significant for several applications. [19][20][21] Furthermore, studies have shown an induced micellar shape transition (sphere to ellipsoidal) in BCPs with temperature increases and/or in the presence of additives. 5,9,10,21,22 Also, via tuning the solvent polarity, these copolymeric surfactants have the potential to undergo even more complex self-assembly at higher orders, adopting arrangements ranging from rod-like to worm-like or vesicular (polymersomes).…”

“…Also, it is widely accepted that the larger the molecular size of a cosolvent, the more significant are its excluded volume effects; this is one of the basic mechanisms supporting making these carbohydrates (sugars) preferential additives. 18,19 Looking at the fact that sugars do not self-assemble, there are few reports on the effects of glucose on BCPs, but it is argued that the stereochemistry of aldohexose can modulate the water structure and apparently tune hydrophobic interactions around the aggregating species due to its high hydration number. Alexandridis and co-workers observed micellar growth/shape transformation induced in a Pluronic s (P105) in the presence of glucose.…”

Block Copolymer Template-Directed Catalytic Systems: Recent Progress and Perspectives

“…In recent years, a lot of interest has been shown by researchers in the field of block copolymer (BCP)-assisted synthesis of functional (nano)materials for various applications, such as membranes [ 1 , 2 ], catalysis [ 3 , 4 , 5 ], drug delivery [ 6 , 7 , 8 , 9 ], gas absorption [ 10 ], etc. The microphase-separated BCPs are known to form periodic nanostructures with different degrees of complexity, ranging from the simplest diBCP morphologies (spherical, cylindrical, gyroidal, or lamellar structures), up to the very complex and sometimes unique nanostructures like “knitting patterns”, multi-helix, or helical torroids [ 11 , 12 , 13 ].…”

Self-Assembly of Block Copolymers

“…Sandra Rodríguez-Fabià et al compare the uptake of carbon dioxide by an aqueous solution of monoethanolamine with a similar solution containing, in addition, a large amount of a PEO-b-PPO-b-PEO triblock copolymer which forms a lyotropic phase. Depending on the amount of CO 2 , the system shows a transition from a lamellar to a hexagonal phase due to an increased swelling of the PEO domains by an increase in the polarity of the mixed solvent [22]. There are many ways to use block copolymers for templating inorganic materials by using their self-assembled structures for hosting the precursors.…”