Chem. J. Chinese Universities ›› 2025, Vol. 46 ›› Issue (11): 20250210.doi: 10.7503/cjcu20250210

• Physical Chemistry • Previous Articles     Next Articles

Formation and Properties of Sodium Dodecyl Sulfonate Vesicles in n-Propanol/Water Mixed Solutions

WU Yanru1, LI Anming²2, GAO Meihua²2(), ZHUANG Wenchang1,2()   

  1. 1.School of Chemistry and Chemical Engineering,Yili Normal University,Yining 835000,China
    2.School of Materials and Chemical Engineering,Xuzhou University of Technology,Xuzhou 221018,China
  • Received:2025-07-31 Online:2025-11-10 Published:2025-09-16
  • Contact: GAO Meihua2, ZHUANG Wenchang E-mail:mhgao@xzit.edu.cn;windchant@xzit.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(22302165);the Jiangsu Provincial Double Innovation Doctoral Plan, China(JSSCBS20221588)

Abstract:

The self-assembly behavior of sodium dodecyl sulfonate(SDS) in n-propanol(NPP)/water mixed solutions was studied using methods such as dynamic light scattering(DLS), transmission electron microscopy(TEM), small-angle X-ray scattering(SAXS), and Fourier transform infrared spectroscopy(FTIR). Experimental results demonstrated that the introduction of NPP significantly enhanced the solubility of SDS. In the 50%(mass ratio) NPP/water mixed solvent, the solubility of SDS reached 225.71 g/L, representing a 93-fold increase compared to the pure water system(2.42 g/L). The study reveals that in the isotropic phase of the SDS/NPP/H₂O ternary system, besides the typical micellar structure, vesicle aggregates are also observed. As the NPP content progressively increased, the vesicular structures gradually transformed into micelles. When the NPP content exceeded 50%(mass ratio), the aggregates within the system primarily existed as micelles. FTIR spectral analysis confirmed the formation of hydrogen bonds between SDS and NPP molecules(—S=O…H—O—), the “water bridge” and “cation(Na⁺) bridge”(—SO₃⁻ …Na⁺…—SO₃⁻) between SDS molecules played crucial roles. These interactions effectively mitigated the electrostatic repulsion between the anionic headgroups, which is pivotal for the formation of the SDS/NPP vesicular phase. Furthermore, SAXS and atomic force microscopy(AFM) confirmed the presence of an interdigitated structure of alkyl chains between two leaflets configuration within the vesicle bilayer membranes, with an interdigitated degree of 28.57%. This highly interdigitated structure of alkyl chains between two leaflets is also an intrinsic factor contributing to the formation and stability of the SDS/NPP vesicles. The SDS/NPP vesicles exhibit excellent stability under various conditions, including long-term storage, high-temperature treatment, and freeze-thaw cycles. Furthermore, they exhibit a notable capacity for encapsulating hydrophilic dyes such as calcein. Additionally, the vesicle membrane demonstrates, permeability towards OH- ions, and the transmembrane permeation process conforms to a first-order kinetic model. This study could deepen the understanding of the aggregation behavior of single-chain amphiphiles and provide valuable insights for the practical application of single-chain amphiphilic molecule vesicles.

Key words: Vesicle, Sodium dodecyl sulfonate, n-Propanol, Self-assembly

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