Metal-Free Synthesis of Cross-Linkable Poly(silyl ether)s Using Cyclosiloxanes

B(C 6 F 5 ) 3 was reported as an efficient metal-free catalyst for synthesis of poly(silyl ether)s through hydrosilylation polyaddition of disilanes with diketones at ambient conditions. In this study, we aimed to develop poly(silyl ether)s via metal-free hydrosilylation reaction between 2,4,6,8-tetramethylcyclotetrasiloxane (TMCS) having four reactive Si–H groups and various diketones. The prepolymers are possible for postfunctionalization and postprocessing because the remaining Si–H groups could undergo thermal cross-linking reactions. It has been reported that the combination of the B(C 6 F 5 ) 3 catalyst and cyclosiloxane causes undesirable gelation due to hydride transfer ring-opening polymerization (HTRP). Based on our previous investigation about the way for suppression of HTRP, we have successfully synthesized five liquid poly(silyl ether)s via reducing reaction time and total monomer concentration. Thermal curing of the prepolymers by self-cross-linking reaction of the residual Si–H groups gave freestanding films with hydrolysis resistance and high thermal stability above 600 °C despite the presence of organic linkers in the main chain. The development of novel poly(silyl ether)s with functionalizable and cross-linkable Si–H groups has further expanded the possibilities for different applications in various functional materials.