Phase behaviour of neem oil based microemulsion formulations

Globally, focus has been given on the development of neem oil based agrochemical formulations by replacing synthetic agro chemical based products. One of the main inert components in liquid agrochemical formulation is petroleum based solvent which has been replaced by water, by solubilizing the neem oil which can act as a pesticide. These water based microemulsions may have the benefit of natural pesticide along with replacement of highly volatile petroleum solvents which create number of problems in agrochemical formulations like irritation to the eyes at the time of manufacturing and applications, phytotoxicity to the plants, etc. In this study we have demonstrated the feasibility of constructing pseudo ternary phase diagrams which are fully diluted with water. The microemulsions were stabilized with mixtures composed of neem oil, nonionic surfactants [371-N (blends of calcium alkyl benzene sulphonate 70% + nonyl phenol ethoxylate 30%) and polyoxyethylene monostearate (Tween-60)] and short chain alcohols as co-surfactants. All the three types; the oil/water, water/oil and the bi-continuous microemulsions could be formed with both the single surfactant as well as with the mixed surfactants. The oil/water microemulsions containing about 10% of oil could be formed. These have been analyzed using Dynamic Light Scattering and conductivity studies. (C) 2012 Elsevier B.V. All rights reserved.