Influence of the Mixed Propoxy/Ethoxy Spacer Arrangement Order and of the Ionic Head Group Nature on the Adsorption and Aggregation of Extended Surfactants

Abstract

Two families of extended surfactants were prepared with the same head groups (carboxylate, sulfate, disodium phosphate) and different intermediate spacer structures. In one there was an average of 7 propylene oxide groups on the side of the tail and an average of 7 ethylene oxide groups on the side of the head, to produce a sequence of two different polarity segments. In the other case the spacer contained the same average numbers of propylene and ethylene oxide groups but in some homogeneous arrangement. The intermediate spacer structure, without ionic head group and in the cases of the carboxylate and sulfate extended surfactants, had a packing density reduction which is associated to the homogeneously alkoxide arrangement in the spacer. Such an arrangement was found to produce about 20% more surface area at the interface, apparently because it results in some plumpness due to the spacer folding to remain close to the interface. Both the critical micelle concentration and occupied interfacial area of the extended surfactant increased with the ionization of the anionic group associated with the electrostatic repulsion effect.

How to Attain an Ultralow Interfacial Tension and a Three‐Phase Behavior with a Surfactant Formulation for Enhanced Oil Recovery: A Review. Part 2. Performance Improvement Trends from Winsor's Premise to Currently Proposed Inter‐ and Intra‐Molecular Mixtures

“…A variety of extended surfactants have been proposed, not only by changing the tail branching [91, 188, 189, 193, 198, 199] but also the head group with sugar or carboxylate, or phosphate combinations. Several applications have been proposed for these surfactants particularly because of their capacity to solubilize natural triglyceride oils in pharmaceutical vehicles, detergency [200], agroindustrial oil extraction [201], crude oil demulsification [202] as well as some others mentioned in a previous review on solubilization [46].…”

“…The extended surfactant performed when the two alkoxides were in sequence, i.e. when there was a continuous progression from lipophilic to hydrophilic [193]. …”

Effects of the Polypropylene Oxide Number on the Surface Properties of a Type of Extended Surfactant

“…The introduction of PO groups can enable the surfactants to extend the hydrocarbon tail further into the oil phase without compromising water solubility (Klaus et al, ). On the water side, insertion of EO groups can enhance the interactions with the water phase (Forgiarini et al, ). This arrangement makes the extended surfactants to have a smooth transition at the oil/water interface or the air/water surface (Klaus et al, ; Phan, Attaphong, & Sabatini, ).…”

Synthesis and characterization of alkyl, propoxy, ethoxy-based frothers

“…Both have some hydrophilic character due to the AOA bridge, but the PO is less hydrophilic due to the hydrophobic ACH 3 branch alternating with the AOA. This difference may give the EO and PO different orientations, from flat at the interface to directed into the water (Thurow and Geisen, 1984;Gélinas et al, 2005;Forgiarini et al, 2010), but, from the work of Stauffer (1968) and Cox et al (1999), we suggest that both PO and EO lie flat on the water side of the interface with the alkyl group directed into the air (Fig. 9) This explanation does not rule out other mechanisms, which invites molecular modeling to try to comprehend.…”