Physicochemical Studies on an All-Purpose Pesticide Spray Adjuvant-(APSA-80)

Abstract

APSA-80, an useful pesticide spray adjuvant is a mixture of 2-[2-(4-nonylphenoxy) ethoxy] ethanol, 1-butanol and tall oil fatty acids. It is strongly surface active and can decrease the surface tension of water to ∼20 mNm⁻¹ at its critical micelle concentration (CMC) of 0.006 g%. APSA-80 itself and its binary mixtures, (APSA-80 + water) and (APSA-80 + isopropylmyristate [IPM]) and ternary mixtures (APSA-80 + water +IPM) can undergo a number of physical changes with rise in temperature; the main changes are in color, turbidity and phases. The ternary mixtures of APSA-80/water/IPM with changing compositions can form mono-, bi-, and triphasic solutions as well as gels and viscous solutions. The gel and viscous phases show characteristic rheological properties of both shear thinning and thickening types. They also show permeation of hydrophilic and oleophilic dyes through them. SEM and optical microscopic measurements have shown interesting surface morphologies of the gels and their vertical projections in three-dimensional pictorial mode. Salts like LiCl, NaCl, KCl, CsCl, MgSO₄, and Al₂(SO₄)₃ can have both minor and major effects on the gel consistencies. The alkanols like ethanol, propanol, and isopropanol are also mild to fairly large gel influencing co solvents. The antibacterial properties of APSA-80 have been studied with two Gram positive bacteria and a yeast; the activities found were moderate.

Keywords:

• Antibacterial property
• APSA-80
• gels
• miscibility with IPM and water
• morphology
• phase behaviors

I.M. thanks Jadavpur University for laboratory facilities of the Centre for Surface Science, Department of Chemistry, to carry out the work. S.P.M. thanks JU for an emeritus professor ship and Indian National Science Academy for an Honorary Scientist position. The authors thank Mr. Pallab Dasgupta of Department of Instrumentation Science, Jadavpur University for SEM measurements and Mr. A. Garai of Polymer Science Unit of Indian Association for the Cultivation of Science for rheological experiments.