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 degrees and 2 degrees 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, H-1, C-13{H-1}, Si-29{H-1} NMR spectroscopies, GPC and MALDI-TOF were also employed. The materials obtained displayed low T-g values (-70.6 to 19.1 degrees C) and were stable upon heating up to T--5%,T-Ar 421.6 degrees C. A trend in T--5%,T-Ar was observed whereby use of a 2 degrees silane leads to higher T--5%,T-Ar compared to those obtained using a 1 degrees 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.

Automated summary

We describe the iron-catalyzed polymerizations of diol and silane monomers to obtain various poly(silylether) products. The reactions are simple and applicable to different types of silane and diol substrates. The obtained materials exhibit low T-g values and high thermal stability, with the use of 2 degrees silane leading to higher thermal stability compared to 1 degree silane.