Preparation of Cyclosilalkylenesiloxane Monomers and Their Cationic ROP

A novel series of cyclosilalkylenesiloxane monomers was prepared having larger alkylene units, hexanylene, octanylene, decanylene, and tetradecanylene, than previously reported. The rings also contain at least one tetramethyldisiloxanylene unit and undergo ring-opening polymerization via the siloxane bond. Thus, poly(1,1,8,8-tetramethyl-9-oxa-1,8-disilanonanylene), poly(1,1,10,10-tetramethyl-11-oxa-1,10-disilaundecanylene), poly(1,1,12,12-tetramethyl-13-oxa-1,12-disilatridecanylene), and poly(1,1,16,16-tetramethyl-17-oxa-1,16-disilaheptadecanylene) were prepared using a strongly acidic ion exchange resin. The polymers were obtained in yields of 74–86%, similar to that obtained for cyclosiloxane equilibration polymerization. The monomers were characterized using ¹H, ¹³C, and ²⁹Si NMR, FTIR, GC-MS, and elemental analysis. The polymers were characterized using ¹H, ¹³C, and ²⁹Si NMR, DSC, TGA, FTIR, GPC, and refractive index.