Phoxim Microcapsules Prepared with Polyurea and Urea–Formaldehyde Resins Differ in Photostability and Insecticidal Activity

Abstract

The application of pesticide microcapsules (MCs) in agriculture is becoming more and more popular. In this study, the effects of different wall materials on the stomach toxicity, contact toxicity, length of efficacy, and photolysis characteristics of pesticide microcapsules were investigated. The results showed that microencapsulation reduced the stomach and contact toxicities of phoxim and prolonged the efficacy of this light-sensitive chemical in the greenhouse test. Neither of the degradation curves for microencapsulated phoxim under ultraviolet light fit a first-order model, although the emulsifiable concentrate (EC) degradation curve fit it well. The phoxim-loaded polyurea microcapsules (PUA-MCs) showed significantly increased UV-resistance ability, stomach toxicity, and contact toxicity compared with the phoxim-loaded urea-formaldehyde microcapsules (UF-MCs). These experiments indicated that it is crucial to select the appropriate wall materials for pesticide microcapsules on the basis of application sites and physicochemical properties of pesticide active ingredients.

Using Coordination Assembly as the Microencapsulation Strategy to Promote the Efficacy and Environmental Safety of Pyraclostrobin

“…Given the integrative cost and the complex manufacturing process, mainstream encapsulation methods adopted to date in the pesticide industry have tended to be interfacial polymerization and in situ polymerization. [6d] Urea‐formaldehyde resins are widely used as wall materials for in situ polymerization, whereas polyurea, polyurethane, and polyamide are usually used for interfacial polymerization . However, formaldehyde, an important precursor for fabricating urea‐formaldehyde resins,[12a] possesses a pungent smell and high toxicity to higher order animals.…”

“…[13a] These polymers (wall materials) are refractory to degradation in the soil and air; thus, the half‐lives of core materials are prolonged. [13b] However, the rapid efficacy of the core material often decreases immediately upon encapsulation, and other factors include its residue and other unforeseeable risks to the environment. With respect to foliar application, rapid efficacy seems more important than long‐lasting efficacy; thus, microcapsule products with quicker release profiles of their core materials are urgently required.…”

Microencapsulation by in situ Polymerization of Amino Resins

“…A wide range of compounds has been encapsulated for applications including pressuresensitive recording materials, 149 adhesives, 52 agrochemicals, 147 perfumes, 150 vegetables oils, 151 consumer products, flame retardants, 152 phase change materials, 153 electronic inks, 154 thermosensitive paper, 155 self-healing agents, 53 drag-reducing agents, 135 smart coatings, 54 and polymer additives. 33 Core materials such as epoxy resins, for instance, are high performance adhesives and promising candidates for self-healing applications.…”

Tunable thermal, mechanical, and controlled-release properties of epoxy phenolic novolac resin microcapsules mediated by diamine crosslinkers

“…[7][8][9][10] For example, MCs fabricated with different polymeric shell materials not only inuence the characteristics of their payload cargoes but also affect the UV-resistance ability, permeability, thermal stability and bioactivity of MCs. 11,12 In addition, some work has also shown that the so segment length, as well as crosslinker type, can bring obvious diversity to the particle size distribution, morphology, loading content and the release behavior of MCs. [13][14][15] Therefore, to design and apply microencapsulation techniques more precisely, it is necessary to investigate the effect of coating materials on the structures and properties of the synthesized capsule shell.…”