Synthesis and properties of MoO3/ZrO2 solid acid catalysts for the preparation of polydimethylsiloxane (PDMS) via octamethylcyclotetrasiloxane (D4) ring-opening

A series of MoO3/ZrO2 catalysts were prepared by impregnation method, and characterized by X-ray diffraction (XRD), specific surface area (BET) and temperature-programmed desorption of NH3 (NH3-TPD). The polydimethylsiloxane (PDMS) was prepared by ring-opening polymerization from D4 and MM with MoO3/ZrO2 catalysts. The effects of MoO3/ZrO2 catalysts preparation conditions on PDMS molecular weight and reaction conversion rate were discussed. Moreover, the effects of reaction conditions on the ring-opening polymerization were also studied. During the preparation of PDMS, the molecular weight of the product can be controlled by adjusting the mass ratio of D4:MM. The MoO3/ZrO2 catalyst was compared with other catalysts during the ring-opening process, and the repeated times of MoO3/ZrO2 catalysts were also studied. The results showed that MoO3/ZrO2 catalyst had more excellent catalytic performance, for ring-opening process, and when the repeated times was more than 5, the catalytic activity decreased significantly. In addition, the kinetics of D4 ring-opening polymerization with the MoO3/ZrO2 catalyst was investigated.