Variable Polymer Properties Driven by Substituent Groups: Investigation on a Trifluorovinylether‐Functionalized Polyfluorene at the C‐9 Position

Abstract

A new polyfluorene PF‐TFVE with functional trifluorovinylether (–OCF=CF 2 ) groups at the C‐9 position is reported. When heated to high temperatures, the polymer converts to a cross‐linked network (PF‐PFCB), which exhibits much lower dielectric constant and dissipation factor at high frequency than a traditional octyl substituted polyfluorene (PFO) (cf., PF‐PFCB: 2.42 and 0.048; PFO: 3.80 and 0.22 @ 30 MHz). The electronic spectra of PF‐PFCB indicate that it exhibits weaker UV–vis absorption and photoluminescent emission than PFO in the solid state, suggesting that the big substituent groups and the cross‐linked networks in PF‐PFCB hinder the conjugation between two fluorene units. This is the first example revealing that dielectric properties of polyfluorenes can be varied by different substituent groups at the C‐9 position. These results indicate that polyfluorenes can not only be considered as semiconductors, but also as insulators. image