Slow-release agricultural pesticide formulations: state of the art

The need for a long-term sustaining of optimal concentrations of applied pesticides in the soil in agriculture resulted in the development of systems for controlled release of active substances. Such systems are based on the use of eco-friendly carrier materials that are harmless to plants, humans and environment. Inorganic substances (e.g., clays or alike substances), biodegradable polymers of natural or synthetic origin, blends of such polymers and their composites with inorganic fillers can be used as carriers. The deposited pesticides are released by diffusion or, in the case of systems based on biodegradable polymers, by degradation of the carrier. Inorganic carriers are usually impregnated with a pesticide. As for polymers, there is a wide range of methods for obtaining forms. Namely, these are the microsphere and nanoparticle formation, film casting, tablet pressing, form gelatinizing, and coprecipitation of a pesticide and a polymer from a solution. Co-extrusion of pesticides with polymers or their composites at temperatures below the degradation temperature of the components is another promising method for obtaining pesticide carriers

Improvement of biocompatibility of high molecular weight poly-3-hydroxybutyrate by blending with its functionalized oligomers

Oligomers of poly-3-hydroxybutyrate (PHB) were prepared by aminolysis of high molecular weight PHB with ethylenediamine and 1,4-diaminobutane. Polymer-oligomer blends (10, 30, and 50% content of the oligomers) were prepared as films by solution casting. As the content of oligomers increased, a gradual increase in the hydrophilicity of the polymer surface was observed, resulting reflected in the water contact angle decrease from 84° to 72–76°. In addition, a moderate decrease in elongation at break, Young's modulus, and tensile strength for the blends were observed as more oligomer was added to the film. Finally, the viability of NIH-3T3 mouse fibroblasts was higher compared to intact PHB when growing in non-prepared polymer/oligomer mixtures. These findings confirm the benefits of the introduction of a hydrophilic functionalized oligomer into the PHB matrix in terms of improving the biocompatibility of the resulting polymer/oligomer blends

Взаимодействие сложных эфиров с хлористым тионилом, катализируемое галогенидами цинка

The ability of esters of primary and secondary alcohols butyl acetate and L‑menthyl acetate (2-isopropyl‑5-methylcyclohexyl acetate) to interact with thionyl chloride in the presence of zinc halides (chloride or bromide) was studied. 1-chlorobutane with a minor admixture of 2-chlorobutane (less than 3.6 %) was the main product of the reactions of butyl acetate. For L‑menthyl acetate, the main product was 2-chloro‑1-isopropyl‑4-methylcyclohexane with minor impurities mainly represented by 1-isopropyl‑4-methylcyclohexene and other six-membered unsaturated hydrocarbons. When ZnBr2 used as a catalyst, impurities of bromo- substituted hydrocarbons were found in the reaction products, which demonstrates the possibility of halogen atoms exchange between zinc halide and the resulting organic products of the reactionИсследована способность сложных эфиров первичного и вторичного спиртов – бутилацетата и L‑ментилацетата (2-изопропил‑5-метилциклогексилацетата), взаимодействовать с тионилхлоридом в присутствии галогенидов (хлорида или бромида) цинка. В качестве основного продукта реакции бутилацетата идентифицирован 1-хлорбутан, с минорной примесью (не превышающей 3.6 %) 2-хлорбутана. Для L‑ментилацетата основным продуктом являлся 2-хлор‑1-изопропил‑4-метилциклогексан; минорные примеси в основном представляли собой 4-метил‑1-изопропилциклогексен и другие непредельные углеводороды с шестичленным циклом. При использовании в качестве катализатора ZnBr2 в продуктах реакции обнаружены примеси бромзамещенных углеводородов, что показывает возможность обмена атомами галогенов между галогенидом цинка и образующимися органическими продуктами реакци