Analysis of the Influence of Alkyl Polyglycoside Surfactant and Cosolvent Structure on Interfacial Tension in Aqueous Formulations versus n-Octane

Abstract

We studied the influence of molecular structural elements of alkyl polyglycoside (APG) surfactants on the interfacial tension (IFT) in aqueous formulations against n-octane. This included the analysis of alkyl and aryl chain length, type and number of sugar-ring head, anomers, addition of cosolvents and effect of salt addition. We found that longer alkyl or aryl chains lead to lower IFT, consistent with data recorded for commercial (mixed) APGs. APGs with only one sugar-ring head had lower IFT than their analog maltose derivates (two-ring head). Intriguingly the stereochemistry of the sugar head (i. e. galactose versus glucose) and the type of anomer showed a significant influence on IFT. The n-octyl-a-D-glucopyranoside anomer had a lower IFT than the corresponding b-anomer. 1-octanol and 1-hexanol were efficient cosolvents consistent with the datasets observed for commercial APGs. Salt addition reduced IFT. Functional groups (aldehyde, amide-methoxy) integrated into the molecular architecture of the APG skeleton were efficient in terms of significantly reducing IFT, suggesting a strategy for the molecular design of advanced APG surfactants. We discuss the results in the context of the hydrophilic-lipophilic deviation (HLD) concept, which we modified so that IFT values are discussed instead of phase behavior.

Alkyl Polyglycoside-Sorbitan Ester Formulations for Improved Oil Recovery

“…The results recorded are presented in Table 8 together with literature values for the CMC values. Longer APG alkyl chains led to lower IFT values, consistent with our previous studies for commercial and pure APGs formulated with 1-alcohols [16,38].…”

“…The APG surfactants alone (2 wt%) did not form micro-emulsion middle phases, and the IFT reached low, but not ultra-low numbers ( Table 4). A micro-emulsion middle phase is an indicator of low or ultra-low IFT [16,18,19,38,39]. The lowest IFT was observed for Agrimul 2062, the most lipophilic molecule of the set.…”

“…This test series included pure APG molecules formulated with Span 20 as cosurfactant. This experimental set was mainly investigated to more rigorously understand the influence of APG and cosurfactant structure on IFT [38], but also to generate experimental data which is directly comparable to molecular dynamics computations which we calculated for deionized water/pure surfactant/pure cosurfactant/n-octane systems [4]. Therefore we prepared these blends in deionized water.…”

New surfactant mixtures for fine foams with slowed drainage

“…We form and study alkaline surfactant mixture containing alkyl polyglucoside (APG) surfactant in addition to the mixture of SLES and CAPB. Besides the readily biodegradability APG surfactants are known and used for their mildness and good stability in wide pH range [19,20]. The presence of APG in the studied mixtures improves significantly the surfactants compatibility and mixed micelles solubilizing capacity at alkaline pH.…”

Deep Eutectic Solvents as New Reaction Media to Produce Alkyl-Glycosides Using Alpha-Amylase from Thermotoga maritima

“…AGs contain a carbohydrate head group such as glucose, galactose, maltose, xylose, α-cyclodextrin, and a hydrocarbon tail, usually a primary alcohol of different chain length of saturated or unsaturated nature [2,3]. Their high biodegradability and a low toxicity make them attractive for many applications such as cosmetics, foods, the extraction of organic dyes, membrane protein research, and pharmaceuticals [4]. The industrial production of alkyl glycosides has been typically achieved by traditional organic chemical procedures.…”