What happens when pesticides are solubilised in binary ionic/zwitterionic-nonionic mixed micelles?

Area of Science:

• Agricultural Chemistry
• Colloid and Surface Science
• Physical Chemistry

Background:

• Surfactants are crucial adjuvants in agricultural sprays, enhancing pesticide solubility and leaf penetration.
• Previous research focused on nonionic surfactants; the behavior of pesticides in ionic, zwitterionic, and mixed surfactant systems is less understood.

Purpose of the Study:

• To investigate how pesticide solubilization affects micellar nanostructures in various surfactant systems (nonionic, anionic, cationic, zwitterionic).
• To determine the influence of electrolytes on these pesticide-surfactant-micelle interactions.

Main Methods:

• Utilized model systems with nonionic (C12E6), anionic (SDS), cationic (DTAB), and zwitterionic (C12PC) surfactants to solubilize three pesticides (Cyprodinil, Azoxystrobin, Difenoconazole).
• Employed Small-Angle Neutron Scattering (SANS) and Nuclear Magnetic Resonance (NMR) spectroscopy to analyze micellar structure and pesticide location.
• Investigated the effects of electrolytes on the systems.

Main Results:

• Pesticide solubilization did not alter the micellar structures of ionic and zwitterionic surfactants alone.
• Electrolytes caused minor elongation of ionic surfactant micelles but did not affect nonionic or zwitterionic micelles.
• Binary mixtures of ionic/zwitterionic and ionic/nonionic surfactants showed altered micelle structures (elongation, shrinkage, dehydration) upon pesticide solubilization, dependent on molar ratios.

Conclusions:

• The type of surfactant significantly influences micellar structural response to pesticide solubilization.
• Mixed surfactant systems are more susceptible to structural changes, potentially affecting pesticide delivery efficacy.
• Findings provide insights into optimizing agri-spray formulations for enhanced pesticide performance.