Abstract
(2-((1-(4-chlorophenyl)-1H-pyrazol-3-yl)oxy)-N-(3,4-dichlorophenyl)-propanamide) is a new oil-soluble compound with good fungicidal activity against Rhizoctonia solani. Chitosan oligosaccharide (COS) is the depolymerization product of chitosan and can be developed into biological pesticides, growth regulators, and fertilizers due to its various bioactivities. COS is an oligomer of β- (1 → 4)-linked d –glucosamine and can be taken as a polyamine. In this study, microcapsules were prepared by interfacial polymerization of oil-soluble methylene diphenyl diisocyanate and water-soluble COS. The effects of several key preparation parameters, e.g., emulsifier dosage, agitation rate during emulsification, and core/shell ratio, on properties of the microcapsules such as the encapsulation efficiency, particle size, and size distribution were investigated. The microcapsules were characterized by infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, etc., and the encapsulation efficiency and release behaviors were investigated. The results show that the microcapsules have a smooth surface and 93.3% of encapsulation efficiency. The microcapsules showed slow-release behavior following a first-order kinetic equation, and the accumulative release rates of the microcapsules with core/shell mass ratios of 8.0/4.0, 8.0/5.0, and 8.0/6.0, were 95.5%, 91.4%, and 90.1%, respectively, on day 30. Due to many high biological activities, biodegradability, and the pure nature of COS, microcapsules formed from COS are promising for applications in controlled release of pesticides, growth regulators, and fertilizer.
Highlights
A certain dosage of emulsifier is added during emulsion preparation to reduce the oil–water interfacial tension and produce a highly stable O/W emulsion [42]
The results clearly show that a higher core/shell ratio gave a higher accumulative release rate
The core material inside can pass through the shell because of the Goodness of Fit (R2)
Summary
As one of the major diseases, rice sheath blight is caused by Rhizoctonia solani Kühn and occurs every year in the word, resulting in a large reduction of rice yield [1]. As it can occur in the whole growth stage of rice, it is necessary to use carriers to release the fungicide slowly in order to cope with the lasting effect of rice sheath blight. One of the most important forms of slow-release carriers is microcapsules, which have core—shell structure cores where active ingredients are coated with natural or synthetic polymers, i.e., shell materials, by physical, chemical, or physicochemical methods [2] and have a range of desirable properties [3,4,5,6]. One of the most important forms of slow-release carriers is microcapsules, which have core—shell structure cores where active ingredients are coated with natural or synthetic polymers, i.e., shell materials, by physical, chemical, or physicochemical methods [2] and have a range of desirable properties [3,4,5,6]. (i) The core active ingredient can be released at a designed rate, which enables improved deinsectization, weed killing, and fungi inhibition
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