Influence of Alkynyl Phosphite Ligands on the Curing of Pt(0)-Catalyzed Preparation of One-Component Silicone Rubber

Graphical The ligands L1 – L3 were obtained by transesterification of three alkynyl alcohols with triisopropyl phosphite and complexed with Karstedt's catalyst to investigate the effect of catalysts on the curing of one-component silicone rubber. The test results showed that the catalyst synthesized by ligand L2 was the most effective. When added to one-component silicone rubber, the silicone rubber cured at 120 C for 6 min and at 150 C for 142 s. It could be stored at room temperature for more than 30 days and at 50 °C for 24 h. The thermal stability and mechanical properties of the silicone rubber are not affected by the catalyst and are enhanced. The development of wide-range temperature-stabilized catalysts for one-component silicone rubber is challenging because the high room temperature activity of Karstedt's catalyst greatly diminishes the storage stability period of one-component silicone rubber. In this work, three catalyst ligands were constructed based on a transesterification reaction between alkynyl alcohols and phosphite, then were complexed with Karstedt's catalyst. The results of research and testing showed that the platinum-alkynyl phosphite catalysts have better room temperature stability, in which the catalyst synthesized with the ligand tris(trimethyldodecynyl) phosphite ( L2 ) enabled the silicone rubber to be stored at room temperature for more than 30 days and cured rapidly at 120 °C. Adding this catalyst not only preserved the original performance properties of silicone rubber but also enhanced its thermal stability and mechanical properties. The ligand acted as a substituent to complex with Karstedt's catalyst to inhibit its activity, thus solving the problem of poor storage stability of one-component silicone rubber at room temperature.