Parameters for Microencapsulation of Rotenone

Interfacial polymerization method using toluene-2,4-di-isocyanate (TDI) and ethylenedi-amine as capsule wall was adopted to prepare rotenone aqueous capsule suspension(CS). Three levels of orthogonal test on emulsifying agents proportion,TDI to ethylenediamine (proportion of mol), capsule wall to capsule nuclear, dosage of dispersant agent, pH, stirring speed of emulsifying and crosslinkage degree were designed to obtain the preparing technology parameters of rotenone CS with highest encapsulation rate and stable release speed. The technology parameters were emulsifier 1210-0204C 1∶ 2 ,TDI-ethylenediamine 2.5∶ 1,capsule wall-capsule muclear 1∶ 1,content of PVA 2.5 mg/g,pH 7.2,stirring speed 1 200 r/min,crosslinkage degree 10%.The critical parameters of 2.49 mg/g rotenone CS such as encapsulation rates, average particle size and the thickness of wall, the stability of photo-degradation, the stability of heating and low temperature storage and releasing speed were determined, and the results showed rotenone CS obtained significant photo-stability and controlling releasing efficiency. Under 125 W artificial ultraviolet radiation for 6 d, the degradation rate of rotenone CS was 35.74%, while the degradation rate of rotenone EC was 100%. The stable releasing time of rotenone CS was 22 d which indicates significant controlling releasing efficiency.