Preparation And Property Of Drug Loading And Controlled Release Polymer Materials

As one of the necessary matters of agricultural production, chemical pesticides are widely used in insect disease prevention, at the same time, they bring about issues such as environmental pollution, residual toxins, harm food safety. Therefore, in recent years, pesticide production is facing with a great change. Abandon high persistent, highly toxic pesticide, exploit low persistent or no persistent pesticides become a important method to reduce pesticide contamination, ensure harvest crops and safeguard human health. Compared with develop new product of pesticides, improve dosage form and formula of existing pesticides, develop new uses have higher percentage of hits and much lower cost. Pesticide slow-release formulations are such new forms that prepare pesticide into necessary dosages, made the pesticide reach the specified location consistently and stably at a specific time, to keep enough residual period. Those could make the dosages, application timing, site of action of the pesticide identical well with actual demand. Slow-release formulations are the most economic and safest preparation of pesticide.Controlled release formulations of pesticide prepared using controlled release technology, provide a new method in use pesticide more effectively, prolong efficacy, saving pesticidal chemical, reduce pollution and use cost. This technology has already been used in agricultural production, more and more new products of controlled release formulations appeared. Controlled release formulations are apt to prepared, easily used and secondary product could also be used. Based on the above considerations, the purpose of this dissertation is focused on thermo-sensitive pesticide controlled release formulations and research on the controlled release property of them. The main work and experimental results are as follows:(1) Deltamethrin microcapsules were prepared through in situ polymerization use urea-methanal and melamine-methanal as coating materials. The effect of urea(melamine)-methanal mole ratio and concentration, pH value, temperature, agitation rate, ratio of core and shell material, emulsifier type and dosage, acidification time and chemical auxiliaries on the formation of microcapsules were discussed through contrast experiment. The optimum experiment condition were concluded. Morphology of the microcapsules were observed by scanning electron microscope(SEM), the photos shows that the del taltamethrin microcapsules prepared by this method appeared regular spheres. Entrapment efficiency of the pesticide microcapsules were measured by high performance liquid chromatography(HPLC), the results showed that the pesticide in the microcapsules were well coated.(2) A series of thermo-sensitive copolymer poly(N-isopropyl acrylamide-co-sodium vinyl sulfonate)(PNTPAAm-co-SVS) were synthesized through solution polymerization, and were characterized by1H-NMR, FT-IR and elemental analysis and TGA. The thermo-sensitive property was studied, pH, added salt and copolymer composition were all have remarkable effect on the Lower Critical Solution Temperature(LCST) of the copolymer. Aggregation behavior of PNIPAAm-co-SVS copolymer in aqueous solution as a function of copolymer composition, added salts, and pH were studied by dynamic laser light scattering. PNIPAAm-co-SVS is a thermo-sensitive polyelectrolyte, for the existence of sulfonic acid group in the polymer chain, the copolymer have a good self-assembly performance, thus it maybe of great practical application value. The self-assembly property of the PNIPAAm-co-SVS copolymer was study via experiments. First, it was self-assmebled into polyelectrolyte multilayer films on the silicon wafer with poly (allylamine) hydrochloride(PAH). The morphology of the multilayer films were observed by atomic force microscope(AFM). Then microcapsules coating CaCO3microparticles and deltamethrin microcrystals were formed through self-assembly technology using PNIPAAm-co-SVS and PAH as shell materials, the morphology of the microcapsules obtained were examined by SEM and transmission electron microscopy(TEM), results showed that microcapsules could successfully formed both on the surface of the CaCO3microparticles and deltamethrin microcrystals. The controlled release property of the microcapsules were studied by HPLC, with the increase of the number of the multilayer films and the increase of temperature, the release rate of deltamethin in the microcapsules decreased definitely in the methanol-water solution.(4) thermo-sensitive nonporous and porous gel loading pesticide were successfully synthesized using NIPAAm as monomer, the optimum experiment condition of preparing hydrogels loading deltamethrin and cyhalothrin were confirmed, composition of the gel was determined through FT-IR and the micro morphology of the gel were observed by SEM. The effect of monomer concentration, molecular weight and dosage of the porogen polyethylene glycol on the swelling rate and kinetics of the gel were then studied. Ultimately, the controlled release property of the thermo-sensitive gel were researched, results showed that PNIPAAm hydrogel have a good controlled release property to deltamethrin, could controlled the deltanmethrin loading in the gel release at different temperatures, this have a wide application prospects in drug and pesticide delivery.