Two-phase aqueous systems of cetyltrimethylammonium bromide/sodium dodecyl sulfate with and without polyethylene glycol

Abstract

Aqueous two-phase systems of cetyltrimethylammonium bromide and sodium dodecyl sulfate mixtures without and with polyethylene glycol (PEG) added have been studied at 313.15 K. The results have shown that PEG has a strong effect on the phase diagram of ATPS and microstructures of surfactants aggregates. The addition of PEG leads to the formation of bigger surfactant aggregates, which can be attributed to both the screening effect and the connection effect of PEG. All ATPS, especially those with PEG added, may have potential applications in separation and purification of biomaterials.

Self-healing hydrogels formed in catanionic surfactant solutions

“…0.24 M stock solutions of each of the surfactants were prepared by dissolving 4.373 g CTAB and 3.460 g SDS separately in 50 mL water at 35 C. CTAB-SDS solutions of various compositions were prepared by mixing these stock solutions at 35 C to obtain a nal volume of 10 mL. In accordance with previous works, [42][43][44][45] we observed that the surfactant solutions became opaque if the SDS content was between 20 and 70 mol% while homogeneous and transparent solutions were obtained outside of this concentration range. We conducted the gelation reactions in CTAB-rich regions of the solutions, i.e., in 0.24 M CTAB-SDS solutions containing 0 to 15 mol% SDS.…”

“…[35][36][37][38][39][40][41] Mixtures of the anionic surfactant SDS and the cationic surfactant cetyltrimethylammonium bromide (CTAB) form mixed micelles in both SDS-rich and CTAB-rich solutions while between these compositions, vesicles and formation of a 1 : 1 precipitate are observed. [42][43][44][45] Here, we prepared physical polyacrylamide (PAAm) hydrogels by micellar copolymerization of AAm with 2 mol% C18 in aqueous CTAB-SDS solutions. Since the Kra point for CTAB in water was reported to be around 20-25 C, 46 both the gelation reactions and the characterization of the physical gels were carried out at 35 C. The surfactant and the initial monomer concentrations during gelation were set to 0.24 M and 5 w/v%, respectively.…”

Self-Healing Hydrogels Formed via Hydrophobic Interactions

“…Aqueous solutions of surfactants of opposite charges, called catanionic surfactants, exhibit unique properties originating from the strong electrostatic interactions between their oppositely charged head groups. Mixtures of the anionic surfactant SDS and the cationic surfactant CTAB form mixed micelles in both SDS-rich and CTAB-rich solutions, whereas between these compositions, vesicles and formation of a 1:1 precipitate are observed [76][77][78][79]. It was shown that the correlation length of 0.24 M CTAB-SDS increases from 0.4 to 2.5 nm as the SDS content of the surfactant mixture is increased from 0 to 15 mol%, leading to increased solubility of the hydrophobic monomer C17.3M in the micellar solution [37].…”