Molecular simulation study on the self-assembly behaviors of zwitterionic heterogemini surfactant in aqueous solution

ABSTRACT

The self-assembly behaviors of a series of zwitterionic heterogemini surfactants C_mH_2m+1-PO^4–(CH₂)₂-N⁺(CH₃)₂-C_nH_2n+1, abbreviated as C_m-P-N-C_n (m, n = 9, 9; 9, 12; 9, 15; 9, 18; 12, 12; 12, 15; 12, 18; 15, 15; 15, 18; 18, 18), have been investigated in aqueous solution by the dissipative particle dynamics (DPD) method. Morphologies such as sphere (S), rod (R), planar grid (PG), lamella (L), honeycomb (H), one-, two-, and three-dimensional tunnels (1DT, 2DT, and 3DT) have been observed showing more diversities than those of the corresponding symmetric gemini surfactants C_m-N-N-C_m (m = 9, 12, 15, 18). With the increase of surfactant concentration in the aqueous solution, a distinct transition path ‘‘S—R—PG—3DT—L—2DT—1DT’’ is proved to be common for all the C_m-P-N-C_n systems. Besides, the hydrophobic chain length has a significant influence on the self-assembly behaviors in the case of m ≠ n. Radial distribution function is an effective method to quantitatively evaluate the interaction and relationship between each functional group in the surfactant molecule and water. Results can provide a new insight into the self-assembly behaviors of zwitterionic heterogemini surfactants and the corresponding applications.

GRAPHICAL ABSTRACT

KEYWORDS:

• Dissipative particle dynamics
• self-assembly
• zwitterionic heterogemini surfactant