Encapsulation of bioinsecticide oil in phenol-urea-formaldehyde terpolymer

Novel microcapsules were developed by in situ polymerization of phenol-urea-formaldehyde (PUF) terpolymer and employed for the first time for the encapsulation of neem oil bioinsecticide. Neem oil's rapid degradation in open environment does not permit its use in crops fields. Therefore, microencapsulation seems to be better method to protect it, make it effective and user-friendly. The prepared PUF microcapsules were analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, optical microscopy and particle size analyzer. The controlled release properties of prepared microcapsules were studied by using loss on drying method and by ultraviolet spectrometry. The release kinetics and stability of prepared microcapsules were studied under different pH and temperature conditions. In conclusion, spherical microcapsules with mean particle size 29.8 mu m and good thermal stability have been developed. They could release core more at alkaline pH (26%) than acidic (9%) and neutral (18%). Microcapsules follow first order release kinetics and are operational at or below 45 degrees C. We propose here further that an environment friendly microcapsule suspension formulation of neem oil is possible for application in agriculture which is not explored yet by using terpolymer.