A novel family of non-ionic gemini surfactants derived from sunflower oil: Synthesis, characterization and physicochemical evaluation

摘要

The present study deals with synthesis and characterization of non-ionic gemini surfactants (GSs) of the type, bis (monoglyceride-1-hydroxymethyl-2-fattyacidester)-alpha,omega-alkanediether, with varying spacer lengths and derived from indigenous natural resource (sunflower oil). Compared to conventional surfactants synthesized from synthetic reagents or available commercially, the natural surfactants show cost-effectiveness and (partial) renewability, in addition to favourable surface and bulk properties. Chemical structures were investigated by FT-IR and H-1 NMR. Thermogravimetric analyses (TGA) showed the stability of GSs at elevated temperatures. Low critical micelle concentration (CMC) values indicate enhanced self-aggregation ability of GS molecules. At CMC, SF-6-SF showed lower surface tension than SF-4-SF due to greater adsorption efficiency. Surfactant adsorption increased with temperature rise, indicating favourable spreading behavior. Dynamic light scattering (DLS) studies revealed transition of surfactant dimer molecules (low concentrations) into micellar structures (= CMC). Surface parameters viz., effectiveness, adsorption efficiency, surface excess concentration and minimum area per GS molecule indicate superior interfacial properties. Relative spontaneities to adsorption and micellization processes were studied by thermodynamic investigations. Viscosity studies showed the existence of both pseudoplastic and dilatant properties. Interestingly, temperature increase caused growth of linear aggregates showing their ability to retain their viscous (pseudoplastic) properties. The applicability of GSs in diverse systems was investigated, based on their physicochemical evaluation. (C) 2018 Elsevier B.V. All rights reserved.