Synthesis and structure–activity relationships of nonionic surfactants with short fluorocarbon chains

The biodegradability of fluorinated surfactants can be improved by reducing the length of the fluorocarbon chain. In this study, ten new nonionic fluorinated surfactants with various hydrophilic and hydrophobic chain lengths were synthesized by means of substitution and ring-opening reactions using methoxypolyethylene glycols (mPEGs) or 2-methoxyethanol, epibromohydrin, and perfluoroalkyl alcohols as raw materials. We measured the static and dynamic surface tension of the synthesized surfactants and used the resulting data to develop structure–activity relationships. We found that mPEG molecular weight was the main determinant of minimum surface tension, and the number of fluorocarbon atoms was the main determinant of critical micelle concentration. Diffusivity decreased with increasing number of fluorocarbon atoms but increased with increasing mPEG molecular weight. Surfactant 5i showed the best performance, lowering the surface tension of water to 17.89 mN/m.