Combined experimental–theoretical investigation on the interactions of Diuron with a urea–formaldehyde matrix: implications for its use as an “intelligent pesticide”

The production of controlled release systems for Diuron aims to reduce some disadvantages of its conventional application and to diminish the associated environmental pollution. In this work, a matrix of urea–formaldehyde containing micro-encapsulated Diuron (Diuron–UF) is proposed to that purpose. The results of the morphology and distribution of particles sizes are expected to promote permeability allowing a water flux and the release of the pesticide. The possible interactions between the UF matrix and Diuron were investigated using experimental and theoretical techniques. The obtained results strongly suggest that the Diuron–UF interactions are weak enough to assure easy release. The shifts in the IR bands are modest, which is in line with the proposal that the interactions arise from H bonding and do not involve the formation of chemical bonds. The in vitro assays showed that the investigated material releases small amounts of the active component for extended periods of time. This behavior is expected to allow a large assimilation of the pesticide by plants, at the same time that it would prevent—or at least reduce—the environmental pollution caused by the Diuron degradation products. The gathered data combined indicate that Diuron–UF materials can be used as “intelligent pesticides”.