title: Evaluation of the Thermosensitive Release Properties of Microspheres Containing an Agrochemical Compound.
abstract: The purpose of this study was to develop a deeper understanding of the key physicochemical parameters involved in the release profiles of microsphere-encapsulated agrochemicals at different temperatures. Microspheres consisting of different polyurethanes (PUs) were prepared using our previously reported solventless microencapsulation technique. Notably, these microspheres exhibited considerable differences in their thermodynamic characteristics, including their glass transition temperature (Tg), extrapolated onset temperature (To) and extrapolated end temperature (Te). At test temperatures below the Toof the PU, only 5-10% of the agrochemical was rapidly released from the microspheres within 1 d, and none was released thereafter. However, at test temperatures above the Toof the PU, the rate of agrochemical release gradually increased with increasing temperatures, and the rate of release from the microspheres was dependent on the composition of the PU. Taken together, these results show that the release profiles of the microspheres were dependent on their thermodynamic characteristics and changes in their PU composition.
authors.affiliation: Health & Crop Sciences Research Laboratory, Sumitomo Chemical Co., Ltd.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Terada
authors.forename: Toshiro
authors.initials: T
authors.lastname: Ohtsubo
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Iwao
authors.forename: Shuji
authors.initials: S
authors.lastname: Noguchi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Itai
mesh_terms: D016573:Agrochemicals / Q000032:analysis*; D065546:Drug Liberation; D008863:Microspheres; D015394:Molecular Structure; D011140:Polyurethanes / Q000138:chemical synthesis / Q000737:chemistry*; D013696:Temperature
chemical_list: D016573:Agrochemicals; D011140:Polyurethanes