Abstract

This work reports selected micellization properties (i.e., micelle shapes, micelle sizes, and critical micelle concentrations) for four polysorbates emulsifiers (polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate) in aqueous media over the temperature range from 283.15 K to 353.15 K at atmospheric pressure (101.3 kPa). The theoretical calculations of the micelle shapes, micelle sizes, and critical micelle concentrations are predicted from the micellar thermodynamic theory. The experimental critical micelle concentrations (CMCs) are estimated from the available surface tension data as a function of surfactant concentrations at each isothermal condition by using an adapted version of the glass transition temperature hyperbola function, which avoids the ambiguity in choosing the fitting ranges. According to the theoretical results, the explored polysorbates display spherical micelles at lower ag-gregation numbers, In contrast, at higher aggregation numbers, polysorbates exhibit rod-shaped micelles, and globular micelles are not allowed. The sizes of micelles are also sensible to temperature showing an increment as the temperature increases. The predicted CMCs show the same temperature behavior observed from experimental determinations, and their predicted values are in good agreement with the calculated experimental values with a maximum absolute average deviation of 0.8%.