title: Physicochemical Characteristics and Slow Release Performances of Chlorpyrifos Encapsulated by Poly(butyl acrylate-co-styrene) with the Cross-Linker Ethylene Glycol Dimethacrylate.
abstract: Chlorpyrifos' application and delivery to the target substrate needs to be controlled to improve its use. Herein, poly(butyl acrylate-co-styrene) (poly(BA/St)) and poly(BA/St/ethylene glycol dimethacrylate (EGDMA)) microcapsules loaded with chlorpyrifos as a slow release formulation were prepared by emulsion polymerization. The effects of structural characteristics on the chlorpyrifos microcapsule particle size, entrapment rate (ER), pesticide loading (PL), and release behaviors in ethyl alcohol were investigated. Fourier transform infrared and thermogravimetric analysis confirmed the successful entrapment of chlorpyrifos. The ER and PL varied with the BA/St monomer ratio, chlorpyrifos/monomer core-to-shell ratio, and EGDMA cross-linker content with consequence that suitable PL was estimated to be smaller than 3.09% and the highest ER was observed as 96.74%. The microcapsule particle size (88.36-101.8 nm) remained mostly constant. The extent of sustainable release decreased with increasing content of BA, St, or chlorpyrifos in the oil phase. Specifically, an adequate degree of cross-linking with EGMDA (0.5-2.5%) increased the extent of sustainable release considerably. However, higher levels of cross-linking with EGDMA (5-10%) reduced the extent of sustainable release. Chlorpyrifos release from specific microcapsules (monomer ratio 1:2 with 0.5% EGDMA or 5 g chlopyrifos) tended to be a diffusion-controlled process, while for others, the kinetics probably indicated the initial rupture release.
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Zideng
authors.initials: Z
authors.lastname: Gao
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Shen
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Sainan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Ren
authors.affiliation: College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Hu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D002214:Capsules / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004390:Chlorpyrifos / Q000737:chemistry*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D019855:Ethylene Glycol / Q000737:chemistry; D007306:Insecticides / Q000737:chemistry*; D010316:Particle Size; D058105:Polymerization; D011137:Polystyrenes / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D002214:Capsules; D003692:Delayed-Action Preparations; D007306:Insecticides; D011137:Polystyrenes; C547381:poly(butyl acrylate-styrene); D019855:Ethylene Glycol; D004390:Chlorpyrifos
keywords: chlorpyrifos; emulsion polymerization; ethylene glycol dimethacrylate; microcapsule; poly(butyl acrylate-co-styrene); slow release