The Preparation And Performance Research Of Bifenazate Microcapsules

Layer-by-layer(LBL) is a kind of technology to preparation of ultrathin membrane, it relies mainly on the electrostatic interaction between polyelectrolyte assembly, on the base layer upon layer deposition of oppositely charged polyelectrolytes, make the nano or micronano microcapsules. The method is simple operation, mild conditions, it can assemble at the molecular level control quantity, membrane structure and the film thickness.This topic with natural polymer polyelectrolyte chitosan and sodium carboxymethyl cellulose as wall materials, the Poor light stability of pesticides bifenazate microcapsule was prepared by layer-by-layer assembly technology. Flowing point test was used to screen the dispersing agents, Ordinary optical microscope and SEM observe the surface of the microcapsules morphology, Zeta potentiometer and laser granulometer determine the different assembly layer the Zeta potential and particle size of microcapsules, the raw materials and the microcapsule were analyzed by FTIR, and ultraviolet spectrophotometry was used to measure drug loading capacity and entrapment efficiency. Studied the salt ion concentration of the liquid in assembly, the change of p H value and assembled layer effects on microcapsule drug release behavior, the drug release data was analyzed to explores the mechanism of drug release microcapsule, Finally, the photolysis rate in different layers under ultraviolet was measured by HPLC.The results show that, SP-3060 is an excellent anionic dispersion stabilizer; SEM and Zeta potential showed that chitosan and sodium carboxymethyl cellulose can alternate deposition in bifenazate surface preparation of microcapsules, preparation of microcapsule reunion is less, the surface smooth level off into a rough, and fold; Assembly size change shows that after assembly in the process of formation of the capsule wall thickness is very thin. FTIR showed no chemical bonds between bifenazate and capsule wall material.Assembly time impact the microcapsules' entrapment efficiency is bigger, polyelectrolyte need 20 minutes to adhesion the bifenazate's surface; the temperature impact the microcapsules' entrapment efficiency is small, at room temperature can cause the assembly behavior very good. When the numbers of assembly layer were 12, 16 and 20, the drug loading capacities were 82%, 81.6% and 78.3%, the times to reach the highest release-rate were prolonged for 1.6, 2.4 and 2.6 times, and the photolysis rates under ultraviolet were decreased to 56%, 68% and 71%, respectively.By changing the polyelectrolyte solution pH and salt concentration, the assembly layer, can control drug release behavior of bifenazate microcapsule. Drug release rate of microcapsules decreased with increasing layer of assembly, when solution pH at 2.0 to 5.0 range increases, the microcapsules of drug release speed increase with the decrease of the first, the lowest in the pH is 4,As the assembly of salt ions concentration increased, microcapsule increase, after take the lead in reducing the rate of drug release of meet minimum when NaCl concentration is 0.5 mol/L.Using empirical formula established drug release kinetics model shows that the number of assembly of 12, 16, 20 of the release of microcapsule preparation mechanism is the same, belongs to the diffusion- erosion combined with releasing mechanism.