ABSTRACT Rapid‐defoaming nonionic Gemini surfactants hold significant application value in processes such as industrial cleaning and photoresist development. In this study, three nonionic Gemini surfactants (B1, B2, and B3) with different polyoxyethylene (EO) chain lengths ( n = 6, 7, and 8) were synthesized via a one‐step method based on 2,5‐di‐tert‐butylhydroquinone. The chemical structures of the resulting compounds were confirmed using Fourier‐transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The foaming behavior, surface tension, wettability, and emulsifying capacity were systematically evaluated. The findings revealed that foam stability for all surfactants remained below 35% and displayed a trend of initial increase followed by decrease as concentration rose, confirming their rapid defoaming characteristics. Under the same concentration, when increasing EO chain length, surface tension remained largely unchanged, while the wetting performance showed a decreasing trend. The emulsifying ability was improved with increasing concentration. This study systematically reveals the critical role of EO chain length in regulating the surface activity and foaming characteristics of nonionic surfactants, providing a theoretical basis for the development of high‐efficiency surfactants.
Xing et al. (Sun,) studied this question.