Studying On The Formation Law And The Influence Factors Of Surfactant Aggregates Loading Chlorpyrifos

With great attention pay to the environmental protection and efficient use of resources, the pesticide agent producing is developing to efficient, safe, low toxic and easy-to-use. Agro-microemulsion can meet the need. Studying the factors on the transparent temperature region of agro-microemulsion, we can develop the scientific of the microemulsion preparation. In addition, liquid crystal phase is the special stage in the microemulsion phase transition, the interface layer forming liquid crystal has obviously viscoelasticity, this viscoelastic systerm can form more stable emulsion. This thesis chose chlorpyrifos as the research object. On the base of the research we have done before, we did more research about surfactant aggregates as drug carrier. The following aspects were studied in this thesis:1. Effects of n-CnH2n+1OH (5≤n≤8) on the transparent temperature region of chlorpyrifos microemulsion were investigated. The results showed that with the increasing of the n and the mixed surfactant content, the formation of microemulsion became easier;When the alcohol and its amount were known, the proportion of surfactants had a great influence on the transparent temperature region of the micro-emulsion; With the increasing of the alcohol content, the upper limit of the transparent temperature declined, and the lower limit of the transparent temperature increased slightly; With the increasing of n, the upper limit of transparent temperature increased mostly, but the changes of the lower limit of transparent temperature was in an irregular course.2. Effects of electrolytes on the transparent temperature region of chlorpyrifos micro-emulsion were investigated. The results showed that the surfactant content could influence on the transparent temperature region of micro-emulsion; Adding electrolytes found with the increasing of cationic content, the upper limit of transparent temperature of mixed systems gradually decreased,the changes of the lower limit of transparent temperature were relatively slight. With the increasing of anionic content, the upper limit of transparent temperature decreased on the whole,and the tendency was related to the anionic content and the anionic structure types,the changes of the lower limit of transparent temperature had no laws; Both in strong acid and strong base solutions, the upper limit of transparent temperature both decreased, and in weak acid solutions the upper limit of transparent temperature reached a maximum. With the increasing of pH values, the lower limit of transparent temperature increased slightly.3. Effects of organic solvents, temperature, n-alcohols and inorganic salt on the formation of liquid crystal phase were investigated to discuss the formation law of liquid crystal system loading chlorphyrifos. The results showed that the substituent in the phenyl ring was advantageous to the formation and maintenance of liquid crystal phase; The system water content rose when the liquid crystalline phase formed and vanished caused by high temperature; With the increasing of the chain length for n-alcohols, the minimum water content for the formation of liquid crystal increased slowly. But when the liquid crystal phase vanished, the maximum water content first rose, then dropped; Adding inorganic salt, the maximum water content needed for the disappearance of liquid crystal phase decreased with hydrated radius of positive ion decreasing, it showed that structure of liquid crystal was unstable.4. Effects of stability of liquid crystal phase were investigated. The results showed that with the increasing of water content, the cloud point of system decreased; Adding n-CnH2n+1OH to the system, cloud point changed similarly with the changes of chain length under the different water content (30%,50%), that was to say when n less than or equal to 5, the changes of cloud point was less, but when n more than 5, the cloud point significantly decreased with the increasing of the chain length for n-alcohols. Diluted the sample to 10g and it was observed that after diluting the particle size of the emulsion increased with the increasing of the chain length for n-alcohols. For the system which contained n-pentanol, the cloud point decreased with the increasing of n-pentanol content, and the particle size of the emulsion after diluted first dropped, then rose.5. By the investigation on the polarizing photos could find that with the water content increasing, the order of liquid crystal microstructure was lamellar liquid crystal and hexagonal liquid crystal; reversed phase hexagonal liquid crystal; lamellar liquid crystal. Adding n-pentanol, the convert order of liquid crystal microstructure did not change, but the convert point moved to the area containing more water. By researching the viscosity of the system, we found the change of viscosity had close relationships with the change of liquid crystal microstructure, with the increasing of the water content the viscosity first rose, then dropped, the high viscosity areas is in the liquid crystal phase. When the water content was 33%, the viscosity of system is the highest, its microstructure is reversed phase hexagonal liquid crystal, then the system came into lamellar liquid crystal, the viscosity significantly decreased. In the lamellar liquid crystal phase, the viscosity had close relationships with the spacing of layers, the viscosity decreased when the spacing of layers increased. Moreover, we found that, the lamellar liquid crystal system which contains 50% water in 25℃was pseudoplastic fluid.