|
Controlled release of the drug through the polymer film, can effectively extend the time of drug action, to enhance the efficacy and reduce dose and side effects, to achieve the purpose of long-term uniform release of the drug. Acetamiprid is a pyridine class of broad-spectrum insecticides, aphids have a very good effect on vegetables, fruit trees, but commonly used formulations EC and WP, ??EC and other traditional formulations need to use a lot of harmful solvents ( such as toluene, xylene, etc.), which greatly polluted environment, currently prohibit the use of the voice of the aromatic hydrocarbon solvent is extremely strong in the developed world, especially in vegetables, fruit, using the EC was strongly resisted. China, as a big agricultural country has important theoretical and practical application prospects of sustained-release pesticide formulations. This article was prepared by two kinds of polymer materials for controlled drug release and sustained-release: First, by the in situ polymerization of acetamiprid / urea-formaldehyde resin microcapsules using urea-formaldehyde resin capsular release control acetamiprid; addition to binding anionic polymerization of styrene and lactide ring-opening polymerization, polystyrene - polylactic acid block copolymer was prepared by using a polylactic acid biodegradable characteristic of polylactic acid segment in the copolymer film is etched into a hole system was polymerized material microporous membrane is expected for controlled drug release and sustained release. This paper and the results are as follows: First, a urea-formaldehyde resin as the carrier, using the in situ polymerization of acetamiprid / urea-formaldehyde resin microcapsules. The ratio of urea and formaldehyde, emulsification time, acidification of time, and curing time preparation conditions on the particle size, morphology, drug loading and encapsulation efficiency of drug-loaded microcapsules and microcapsules release performance, storage performance studied. The optimum conditions. Acetamiprid / urea-formaldehyde resin microcapsules prepared: urea formaldehyde molar ratio of 1:1.8, emulsification time 1h, acidification time 1h, the curing time of 2h. Under optimum conditions obtained pyridine acetamiprid / urea-formaldehyde resin microcapsules regular morphology, relatively smooth surface; average particle size of 2-3 microns, uniform particle size distribution; drug encapsulation rate of 60% or more. Optimum conditions obtained pyridine acetamiprid / urea-formaldehyde resin microcapsules about 45% of the drug is released in about a month after 4 months; stored at room temperature and 60 ℃, form a complete, has not broken and the quality has changed little, indicating that the resulting microcapsules have good slow-release effect and storage performance. Second, bound styrene anionic polymerization and lactide ring-opening polymerization to prepare a polystyrene - polylactic acid block copolymer (PS-b-PDLLA), and to explore the polylactic acid segment is etched into a hole prepared polymerization method was microporous film. 1. Anionic polymerization the terminal hydroxyl polystyrene (PSOH) for macromolecules and PSOH initiators D, L-lactide ester (D, L-LA) to ring-opening polymerization, the successful preparation of PS-b- PDLLA diblock copolymers using NMR, IR, gel permeation chromatography, differential scanning calorimetry of polymers were characterized. The resulting block copolymer solution was cast to the film, the phase state of the block copolymer were observed by phase contrast microscopy and compared with the phase behavior of the blend membranes of PS and PDLLA. The results show that the better compatibility of the two molecular chain in the block copolymer, the phenomenon of phase separation is not obvious, but the phase separation phenomenon of blend films is very obvious. The block copolymer films immersed in a lye etching after 10 days, and the surface morphology of the polymer film with a scanning electron microscope, the results show that the polymer porous membrane by etching method can be expected for controlled drug release and sustained release.
|