Structure-properties relationship of tetrafluorostyrene-based monomers and polymers containing different donor moieties

A new series of monomers consisting of electron-deficient tetrafluorobenzene fragment and electron-donating units such as carbazole, di-tert-butyl carbazole, 9,9-dimethyl acridan and phenothiazine was prepared. Polymers containing well-defined donor-acceptor side chains were obtained via classical free radical polymerization of previously synthesized monomers. Comparative study of photophysical, electrochemical and thermal properties of the synthesized compounds was carried out. It was shown, that emission colour of the compounds from violet to yellow can be effectively adjusted by manipulation of the connected electron-donating fragments. The energy gaps of the compounds can also be fine-tuned by changing the moieties linked to the para-position of pentafluorostyrene moiety. Experimental optical energy gap values varied from 3.57 eV and 3.62 eV for carbazole based monomer and polymer to 2.99 eV and 3.24 for phenothiazine based monomer and polymer. Band gap values of polymers were found to be close to those of the corresponding monomers. The monomers demonstrated violet to yellow fluorescence in the solid state with quantum yields ranging from 1 to 22%. The solid films of polymers demonstrated blue to greenish fluorescence in the region of 456–512 nm with fluorescence quantum yields varying from 1 to 9 %. Monomers exhibited aggregation induced emission enhancement. Pholuminescence quantum yields of their solid samples were found to be higher than those of dilute solutions. Polymers exhibited higher thermal stability, in respect to the corresponding monomers, with 5% weigh loss temperatures reaching 411 °C.