Yazar "Çeliker, Tuğba" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Öğe
    Hollow microspherical carbazole-based conjugated polymers by photoinduced step-growth polymerization
    (Royal Society of Chemistry, 2021) Çeliker, Tuğba; Suerkan, Ali; Altınışık, Sinem; Akgün, Mert; Koyuncu, Sermet; Yağcı, Yusuf
    A new photochemical approach for the synthesis of metal-free three-dimensional hollow spherical conjugated polymers is described. Irradiation of solutions containing a specially designed monomer, namely 4,4 '-bis(N-carbazolyl)-1,1 '-biphenyl (CBP) possessing both carbazole and biphenyl units, in the presence of iodonium salt (Ph2I+PF6-) at 350 nm resulted in the formation of a dark colored corresponding polymer, poly(4,4 '-bis(N-carbazolyl)-1,1 '-biphenyl) (PCBP). Polymerization proceeds through a step-growth mechanism by successive electron transfer between CBP and the iodonium ion within the photochemically formed exciplex, proton release and radical coupling reactions. The obtained polymers were characterized by UV-vis, H-1-NMR, GPC, CV and BET analyses. Dedoping of self-assembled microspheres with a significant distance resulted in more uniform spherical formations as evidenced by AFM and TEM investigations.
  • Küçük Resim
    Öğe
    Photoinduced step-growth polymerizations of thiophene-carbazole based covalent organic polymer
    (Elsevier Sci Ltd, 2023) Çeliker, Tuğba; Altınışık, Sinem; Yağcı, Yusuf; Koyuncu, Sermet
    A novel metal-free photochemical method for the synthesis of porous conjugated polymers was used to investigate the effects of introducing thiophene co-monomer to the carbazole-based polymer, 4,4′-bis(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)-1,1′-biphenyl (CBP–Th), in terms of its structural, optical, electrochemical and morphological properties. Irradiation of a CBP-Th monomer solution led to the formation of a dark-colored polymer, PCBP-Th, and the role of thiophene on polymerization was investigated, involving electron transfer between CBP-Th and the iodonium ion in the exciplex produced by proton release and radical coupling reactions. The UV–Vis spectra broadened and redshifted due to the elongation of conjugation and solid-state π-π interactions by extra thiophene additive after the polymerization process. The addition of thiophene co-monomer also resulted in decreasing the onset potentials and thus slightly raised HOMO positions determined by the DPV technique. In theoretical calculations, it has been observed that the charge distribution of PCBP-Th at HOMO is over the entire conjugated structure and it has localization in thiophene-thiophene bridges at LUMO. Since the thiophene co-monomer changes the intermolecular distance, the thermal stability of PCBP-Th polymers decreases and accordingly increases the amorphous characters. According to AFM, TEM and SEM images, introducing the thiophene co-monomer led to the formation of larger clusters, resulting in a more pronounced surface texture on both the powders and thin films.