One Step Synthesis, Characterization of Modified Montmorillonite with Hydrothermal-Assist for Triazolone Sustained Release System with pH Sensitivity

Abstract

Montmorillonite K-10 clay (MMT) was surface-modified by sodium dodecyl sulfate (SDS) and grafted with KH-550 coupling agent to construct "Hy-MMT" organic modified structure in one step with hydrothermal-assist. Different sustained release systems were prepared through changing the temperature during the hydrothermal process. The characterization results illustrated the mechanism of the hydrothermal assist in intercalation during the organic modification. It was also proved that the triazolone loaded in the sustained release system existed as homogeneous in the pores as amorphous state by DSC analysis. According to SEM and TEM observation, the surface of original MMT or modified MMT without hydrothermal assist presented rough particles, which belonged to the SDS and KH-550 without intercalation into the layer structure which is in accordance with the contact angles of the samples. The experimental results indicated that the adsorption capacity (AC) of Hy-60-MMT showed the best due to its mild react condition the successfully intercalated by SDS and KH-550 by the assist of the hydrothermal treatment. Its AC for triazolone was significantly increased to 29.8 mg/g comparing to MMT without modification which showed no capacity for triazolone adsorption. The as-synthesized system also showed significant pH sensitivity with a sequence of pH = 7 > pH = 3 > pH = 5 > pH = 9 in release speed indicating that the sustained release system can be well stored in mild acid or basic environment and activated while sprayed into earth or plants under neutral condition.