Dehydrocoupling Polymerization: Poly(silylether) Synthesis by Using an Iron β-Diketiminate Catalyst

We describe the iron-catalyzed polymerizations of diol and silane monomers to obtain fourteen different poly(silylether) products with number average molecular weights (M_n ) up to 36.3 kDa. The polymerization reactions developed in this study are operationally simple and applicable to 1° and 2° silane monomer substrates and a range of benzylic and aliphatic diol substrates as well as one polyol example. The polymers were characterized by IR spectroscopy, DSC and TGA and, where solubility allowed, ¹ H, ¹³ C{¹ H}, ²⁹ Si{¹ H} NMR spectroscopies, GPC and MALDI-TOF were also employed. The materials obtained displayed low T_g values (-70.6 to 19.1 °C) and were stable upon heating up to T_-5%,Ar 421.6 °C. A trend in T_-5%,Ar was observed whereby use of a 2° silane leads to higher T_-5%,Ar compared to those obtained using a 1° silane. Reaction monitoring was undertaken by in situ gas evolution studies coupled with GPC analysis to follow the progression of chain-length growth which confirmed a condensation polymerization-type mechanism.