Preparation and characterization of dicarboxylic acid modified starch-clay composites as carriers for pesticide delivery

Abstract

Modified starch based composites were prepared with bentonite/organobentonite for their potential use as carriers for pesticide delivery. Soluble starch was esterified with dicarboxylic acid chlorides. Mean degree of substitution of modified starches varied from 0.101 to 0.353. Composites were prepared by solution intercalation method using these esterified starches and bentonite or cetyltrimethylammonium bentonite as filler materials. TEM analysis of composites showed well exfoliated/intercalated structures. Atrazine as a model pesticide was encapsulated in them and encapsulation was found to be 83.52–92.83%. These composites were also found to be acted as controlled release matrices for atrazine and release pattern was diffusion controlled. As compared to the commercially available wettable powder formulation, the composites were able to release encapsulated atrazine in water for a longer period. The research showed that the prepared composites could be further investigated as carriers for controlled release formulations of pesticides to minimize dose and number of applications.

Keywords

• Polymer-clay composites
• Esterified starch
• Controlled release formulation
• Atrazine
• Organobentonites
• Release kinetics