Preparation and dilute solution properties of model gemini nonionic surfactants

Area of Science:

• * Materials Science
• * Colloid and Surface Chemistry

Background:

• * Nonionic gemini surfactants offer unique properties compared to conventional surfactants.
• * Understanding their synthesis and behavior is crucial for developing advanced materials.

Purpose of the Study:

• * To synthesize and characterize novel dimeric poly(ethylene oxide) surfactants (GemnEm).
• * To investigate the influence of alkyl chain length (n) and ethylene oxide units (m) on surfactant properties.
• * To determine water solubility, cloud temperatures, and critical micelle concentrations (CMCs).

Main Methods:

• * Synthesis of GemnEm surfactants with varying n (12, 14, 20) and m (5, 10, 15, 20, 30).
• * Turbidity measurements to determine water solubility and cloud temperatures at 1 wt%.
• * Pyrene fluorescence method to measure critical micelle concentrations (CMCs).

Main Results:

• * Cloud temperatures increase with ethylene oxide units (m) and decrease with alkyl chain length (n).
• * Surfactants with large m exhibited cloud temperatures above 100°C.
• * CMC values ranged from 10(-7) to 10(-6) M, with lower values for larger n and smaller m.
• * Mixtures with conventional surfactants followed ideal mixing models.

Conclusions:

• * The synthesized nonionic gemini surfactants exhibit tunable properties based on their molecular structure.
• * These surfactants demonstrate potential for various applications due to their controlled solubility and aggregation behavior.
• * The findings provide valuable insights into the structure-property relationships of nonionic gemini surfactants.