in interfacial polycondensation, the two reactants in a polycondensation meet at an interface and react rapidly. the basis of this method is the classical schotten-baumann reaction between an acid chloride and a compound containing an active hydrogen atom, such as an amine or alcohol, polyesters, polyurea, polyurethane. under the right conditions, thin flexible walls form rapidly at the interface. a solution of the pesticide and a diacid chloride are emulsified in water and an aqueous solution containing an amine and a polyfunctional isocyanate is added. base is present to neutralize the acid formed during the reaction. condensed polymer walls form instantaneously at the interface of the emulsion droplets.