Preparation of cyclosilalkylenesiloxane monomers and their cationic ROP

A novel series of cyclosilalkylenesiloxane monomers was prepared having lar ger alkylene units, hexanylene, octanylene, decanylene, and tetradecanylene , than previously reported, The rings also contain at least one tetramethly ldisiloxanylene unit and undergo ring-opening polymerization via the siloxa ne 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-tet ramethyl-13-oxa-1,12-disilatridecanylene), and poly(1,1,16,16-tetramethyl-1 7-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 H-1, C-13, and Si-29 NMR, FTIR, GC-MS, and elemen tal analysis. The polymers were characterized using H-1, C-13, and Si-29 NM R, DSC, TGA, FTIR, GPC, and refractive index.