胆固醇改性海藻酸钠衍生物对高效氯氟氰菊酯水乳剂稳定性的影响

采用反相乳化法制备了以烷基糖苷(APG)为乳化剂的高效氯氟氰菊酯水乳剂,并从静置稳定性、离心稳定性、分散稳定性、冻融稳定性、液滴粒径、Zeta电位及黏度等方面,研究了胆固醇接枝改性海藻酸钠衍生物(CSAD)对水乳剂物理化学性质的影响。结果表明:与单独使用烷基糖苷的乳液相比,加入0.2~1.0 g/L的CSAD可使水乳剂的稳定性明显提高,其离心稳定性参数最优可达85.19%,Zeta电位值最高为-41.9 m V;但随着两亲性聚合物CSAD浓度的增大,乳液稳定性逐渐降低,体系下层很快析出透明或半透明的液体。差示扫描量热(DSC)法测定结果显示,加入CSAD后显著提高了水乳剂的冻融稳定性,其乳液结晶温度从-13.25℃下降至-18.06℃。由此推断,适量的CSAD可通过疏水作用与APG形成混合胶束,从而通过改变体系的空间效应而提高乳液的稳定性。

Effect of amphiphilic cholesteryl grafted sodium alginate derivative on the stability of lambda-cyhalothrin in water emulsion

The effect of amphiphilic cholesteryl grafted sodium alginate derivative (CSAD) and nonionic surfactant alkyl poly-glycosides (APG) on the physicochemical properties of pesticide lambda-cyhalothrin in water emulsions was systematically investigated in terms of standing stability, centrifugal stability, dispersion stability,crystallization temperature, droplet size, Zeta potential and viscosity. Results showed that the emulsions with 0.2-1.0 g/L CSAD displayed excellent stability. By using the most optimized concentration of CSAD, the centrifugal stability index of the water emulsions increased to 85.19%. Zeta potential value increased gradually to -41.9 mV followed by a gradual decrease. However, the stability sharply decreased with the increasing polymer concentration. Furthermore, differential scanning calorimetry (DSC) technology was employed to study the freeze-thaw stability of pesticide emulsions. The data showed that the freezing point shifted from -18.06 ℃ to -13.25 ℃ with the addition of CSAD. It revealed that the water emulsions had good stability at low temperature. Therefore, appropriate concentration of CSAD could improve the stability of the emulsion possibly due to the formation of the CSAD-APG complexes.