(78b) Extended Surfactants: Impact of Molecular Structure on Micellization

We investigate non-ionic surfactants in terms of their ability to solubilize in aqueous solutions compounds that are sparingly water-soluble, including environmental contaminants and pharmaceutical actives. Fundamental information about the non-ionic surfactant self-assembly in aqueous solution can be used to assess the surfactant affinity to hydrophobic compounds, and its compatibility and potential synergism with other surfactants, polymers, and/or particles typically used in formulations. [Sarkar & Alexandridis, J. Phys. Chem. B 2010, 114 (13), 4485-4494; DOI: 10.1021/jp910939q] [Bodratti et al., Adv. Colloid Interface Sci. 2017, 244, 132-163; DOI: 10.1016/j.cis.2016.09.003] We consider here homologous series of surfactants consisting of a C10-alcohol with varying degrees of ethoxylation, and report results on the onset of micellization (cmc), micellization thermodynamics, and micelle local environment in aqueous solutions. [Bodratti et al., J. Surfact. Deterg. 2019, 22, in press; DOI: 10.1002/jsde.12284] Structure-property relations are developed by examining the effects on self-assembly of placing propylene oxide segments between the polyoxyethylene headgroup and the alkyl tail of the surfactant, thus creating “extended” surfactants with a gradient of amphiphilicity along the surfactant chain. The micellization behavior of low-molecular weight alkyl polyethylene glycol ether surfactants is compared to that of high molecular weight polyoxyethylene-polyoxypropylene surfactants. [Kaizu & Alexandridis, J. Mol. Liq. 2015, 210, 20-28; DOI: 10.1016/j.molliq.2015.04.039] [Bodratti & Alexandridis, J. Funct. Biomater. 2018, 9 (1), 11; DOI: 10.3390/jfb9010011]