Synthesis and properties of sodium stearyl polyoxypropylene acetates

Abstract Sodium stearyl polyoxypropylene acetates (SC 18 P p C, p = 3, 6, 9) were synthesized through a two‐step process involving propoxylation of stearyl alcohol and subsequent carboxymethylation. Stearyl polyoxypropylene acetic acids (C 18 P p C, p = 3, 6, 9), the acidified products of SC 18 P p C, were characterized by FT‐IR, 1 H‐NMR, and ESI‐MS. The properties of SC 18 P p C were extensively investigated and compared with sodium dodecanoate (SD) and sodium stearate (SS). The solubility of SC 18 P p C in cold water was enhanced. Kraft temperature (T k ) of SC 18 P 3 C is 40°C which is significantly lower than SS, and T k of SC 18 P p C ( p = 6, 9) are even less than 0°C. SC 18 P p C exhibits overall greater hard water resistance compared to SD and SS with the hardness of 0 to 450 mg/L. The hard water resistance of SC 18 P p C escalates proportionally with the length of the spacer, and the aqueous solution of SC 18 P 9 C retains its clarity even when exposed to the hard water of 450 mg/L, the maximum hardness level of Chinese tap water. SC 18 P p C demonstrates efficiency and effectiveness in reducing surface tension, as well as better foaming, emulsification and wetting power compared to SD and SS. These improved properties make SC 18 P p C ( p = 3, 6) more effective in detergency on three typical soiled fabrics compared to that of sodium soap. Specifically, the detergency to sebum‐stained fabric of SC 18 P 3 C exhibits 1.5 times and 1.3 times improvement compared to SD and SS, respectively. Therefore, it is recommended to incorporate SC 18 P p C ( p = 3, 6) in the detergent formulations for washing intimate apparel in tap water.