Synthesis of Highly Fluorescent and Soluble 1,2,4‐Linking Hyperbranched Poly(arylenevinylene) Featuring Intramolecular Energy Funneling

The synthesis and optical properties of a highly soluble (>200 mg mL−1) and highly fluorescent (ΦF in film = 0.64) 1,2,4‐linking hyperbranched poly(arylenevinylene) (1,2,4‐hb‐PAV) prepared via Wittig reaction of A3 (biphenyl‐tricarbaldehyde) and B2 (phosphonium salt) monomers is reported. The molecular weight of 1,2,4‐hb‐PAV can be precisely controlled by the amount of the base (NaOCH3) used in the polymerization. The absorption and photoluminescence (PL) spectra of 1,2,4‐hb‐PAV shows distinct red‐shifts compared to conventional 1,3,5‐linking hyperbranched poly(arylenevinylene) (1,3,5‐hb‐PAV), attributed to the extended π‐conjugation along ortho‐ (1,2‐) and para‐ (1,4‐) links. The inherent energy gradient from the shorter branches to the longer conjugated stem in 1,2,4‐hb‐PAV enabled a characteristic energy funneling effect, which is absent in conventional hyperbranched polymer of 1,3,5‐hb‐PAV.