Anionic ring-opening polymerization of ferrocenylcyclosiloxanes: a comprehensive structural study

In this study, a comprehensive structural analysis of the linear redox-active ferrocenyl-containing polysiloxanes (FPSs) was performed by the liquid-state ¹H, ¹³C, and ²⁹Si nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and cyclic voltammetry. FPSs with tunable Fc unit content ranging from 20 to 100 mol% were obtained by anionic ring-opening polymerization (AROP). The ²⁹Si NMR spectroscopy indicates the successful anionic homopolymerization of the mono- and tetraferrocenyl-substituted cyclotetrasiloxanes (Fc₄D₄ and Fc₁D₄) by appearance of new signals of Si atoms corresponding to a polymer backbone. An analysis of pentad assignments in ²⁹Si NMR determined the anionic copolymerization of Fc₄D₄ with D₄ by indicating signals of neighboring Si atoms from different types of polymer units (D^F and D), which differ from the signals of homopolymers. The Mayo-Lewis copolymerization constants of Fc₄D₄ and D₄ were determined by the Fineman–Ross method. The molecular masses and unimodal molecular weight distribution of FPSs were estimated by using GPC. FPSs possess redox-activity. Thus, the proposed comprehensive approach analyzes structural features of the functional silicones with enhanced redox properties, which can be applied in (opto)electronics, coatings, and biomedicine.