High‐temperature platinum‐catalyzed hydrosilylation and dehydrocoupling cross‐linking of silicones

Abstract

We propose to use the platinum(II) C,N‐cyclometalated complex (PCC) to catalyze the hydrosilylation and dehydrocoupling reactions of high molecular weight polysiloxanes at elevated temperatures (above 100°C). PCC was prepared via a three‐step procedure consisting of the 2‐hydrazinopyridine synthesis, its treatment with 3‐methoxy‐4‐(prop‐2‐yn‐1‐yloxy)benzaldehyde, and coupling of the obtained product with cis‐[PtCl2(CNXyl)2]. This complex exhibits thermal stability up to 150°C even at heating in air. PCC allows carrying out the cross‐linking of vinyl‐terminated polydimethylsiloxane (V‐PDMS) and polymethylhydrosiloxane (PMHS) by hydrosilylation, as well as PMHS dehydrocoupling cross‐linking at 150 and 120°C, respectively. The coupling (cross‐linking) patterns were successfully confirmed by 1H, 13C, and 29Si solid‐state NMR spectroscopy. The thermal and swelling characteristics and the transparency of the obtained silicone materials indicate the absence of aggregation of platinum particles.