Catalytic Activity of Maghnite-H+ in the Synthesis of Polyphenylmethylsiloxane under Mild and Solvent-free Conditions

Abstract

In this study, a new and easy strategy was discussed for the purpose of synthesizing of a polymer of phenylmethylcyclosiloxane type (PPMS). The cationic ring opening polymerization of triphenyltrimethylcyclotrisiloxane (D₃^Ph,Me) was initiated by a solid, efficient and environmentally-friendly catalyst called Maghnite-H⁺. Maghnite-H⁺ is a natural clay composed essentially of montmorillonite, it is activated with an acid treatment by replacing the interlayer ions by protons, that results to the increase of the basal space, this may be confirmed by XRD analysis. The reaction was carried out without solvent at different temperatures and for different periods of time, using also several catalyst contents. Subsequently, the operating conditions were opted in order to obtain a maximum yield of the linear polymer and a high average molecular mass as well. The structure of polymers obtained was confirmed by IR analysis. ¹H NMR and ¹³C NMR analyzes were used to follow the crosslinking of polymer chains over time. The thermal behavior was investigated by DSC analysis. The average molecular mass and the polydispersity indices were determined by GPC.