Tuning micellar characteristics, mildness and antimicrobial activity of biodegradable surfactants

Abstract

There are a wide variety of chemical compounds, but surfactants are unique. One of the main functions of surfactant is to amend the interfacial properties, to self-aggregate and to solubilize in the micelles. In addition to sharing these properties, surfactants can also be used for multiple purposes including modification of wettability, detergency, and displacement of liquid phases through porous media, as well as in the stabilization or destabilization of dispersions (including foams, froths, and emulsions), respectively. Thus, they can be applied to a wide range of tangible applications, such as mineral processing, petroleum refining, biological systems, crop fortification, health and personal care products. Along with specific surfactants, the mixed surfactants comprising combinations of anionic-nonionic, anionic-amphoteric, nonionic- amphoteric, etc. are increasingly used in applications like when one of the primary surfactant is mixed with a co-surfactant, the average surface area of the surfactant head is altered which ultimately influences the way the micelles are structured. Formulators use this method as one of the ways to adjust the performance of their products. Mixing different types of surfactants can also be beneficial, since it can enhance the cleaning efficacy, foaming and sensory properties. Understanding and utilizing interactions between surfactants and co surfactants in the context of cosmetics and personal care products is critical to the development of successful products. In terms of personal care products, the debate about replacing sulfates continues to gain momentum globally. Hence, it would be more appropriate to replace it with another anionic surfactant or to increase the levels of secondary surfactants or to use surfactant mixtures containing different types of surfactants. Consequently, the present study is primarily concerned with understanding the phase behaviour and self-assembly structures of biodegradable surfactants like anionic surfactants, sodium lauryl ether sulfate (SLES), alpha olefin sulphonate (AOS)non-ionic lauramine oxide (LO), cocamide monoethanolamine (CMEA), decyl glucoside (DG) and zwitterionic cocamidopropyl betaine (CAPB), Cocamidopropyl hydroxysultaine (CAPH), sodium cocoamphoacetate (SCAA). In addition to these commercially available surfactants, we also synthesized novel maleic and succinate acid-based surfactants. Following that, several combinations of surfactant mixtures are prepared along with additives. Most of these surfactants also belong to the sulfate-free surfactant class, which depicted to have less skin irritation as compare to sulfated surfactants. Hitherto, there has been little published information on the phase behaviour, rheology, or foaming formation of these surfactants alone or in mixtures. There is a high probability that this information will prove extremely useful to understand the interactions between these mixtures of sulfate-free surfactants. Several innovative solutions were envisaged as part of a study designed to find advanced ways to formulate products using various combinations of surfactants. As a result of performing a thorough and systematic study, an understanding of the self aggregation pattern, size, morphology, phase behaviour, rheology, and foaming behaviour of the various mixed surfactants systems utilizing the above discussed surfactants has been gained.