Synthesis and properties of sodium stearyl polyoxypropylene acetates

Sodium stearyl polyoxypropylene acetates (SC18PpC, p = 3, 6, 9) were synthesized through a two‐step process involving propoxylation of stearyl alcohol and subsequent carboxymethylation. Stearyl polyoxypropylene acetic acids (C18PpC, p = 3, 6, 9), the acidified products of SC18PpC, were characterized by FT‐IR, 1H‐NMR, and ESI‐MS. The properties of SC18PpC were extensively investigated and compared with sodium dodecanoate (SD) and sodium stearate (SS). The solubility of SC18PpC in cold water was enhanced. Kraft temperature (Tk) of SC18P3C is 40°C which is significantly lower than SS, and Tk of SC18PpC (p = 6, 9) are even less than 0°C. SC18PpC 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 SC18PpC escalates proportionally with the length of the spacer, and the aqueous solution of SC18P9C retains its clarity even when exposed to the hard water of 450 mg/L, the maximum hardness level of Chinese tap water. SC18PpC 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 SC18PpC (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 SC18P3C exhibits 1.5 times and 1.3 times improvement compared to SD and SS, respectively. Therefore, it is recommended to incorporate SC18PpC (p = 3, 6) in the detergent formulations for washing intimate apparel in tap water.