Novel Functional Conjugated Polymers and Polynorbornenes with Nanographenes: Synthesis and Applications for Photoluminescence, Electrochromism and Highly Selective Dispersion for Semiconducting Single-Walled Nanotubes

• Main Authors: Po-I Wang, 王柏翊
• Other Authors: Der-Jang Liaw
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/68528002956554020979

碩士 === 國立臺灣科技大學 === 化學工程系 === 104 === First of all, conjugated polymers, poly(phenylene-fluorene) P1 and poly(triphenylbenzene-fluorene) P2 with hexaphenylbenzene (HPB) as pending side group were prepared through Suzuki coupling. The HPB moiety of P1 and P2 can be oxidatively cyclodehydrogenated with FeCl3, yielding polymer P3 and P4 with hexa-peri-hexabenzocoronene (i.e., nanographene) units. The cyclodehydrogenation of P3 and P4 was confirmed by FT-IR spectroscopy and X-ray powder diffraction of P3 and P4 both revealed the size of nanographene approximately 1.3 nm. The glass transition temperatures (Tg) of P1 and P2 were 202 °C and 235 °C, respectively. Both P3 and P4 with nanographenes possessed Tg higher than 300 °C. Compared to P3, P4 with triphenzlbenyene moiety in backbones can be well dispersed without aggregation in N-Cyclohexyl-2-pyrrolidone (CHP), confirmed by UV-Vis absorption spectroscopy, photoluminescence spectroscopy (PL) and photoluminescence-excitation (PLE) maps. The second section, a new triphenylamine-alt-fluorene based conjugated copolymer, HPBPYFL6, with hexaphenylbenzene (HPB) and pyrene as asymmetrical pendant groups was synthesized. HPBPYFL6 possessed a high glass transition temperature at 260 °C and a 10% weight-loss temperature at 503 °C. HPBPYFL6 bearing a pyrene moiety had a solvatochromic fluorescence shift from a green to orange emission as the polarity of the solvent increased. Conjugated polymer films exhibited reversible electrochromic behaviour with a colour change from pale yellow to deep blue upon electrochemical oxidation and high absorbance in the near-infrared (NIR) region. The strong NIR electrochromic absorbance of HPBPYFL6 was attributed to intervalence charge transfer by the incorporation of the HPB moiety. Furthermore, the electrochromic mechanism was interpreted by DFT calculation and the simulated NIR electrochromic spectra of model compound HPBPYFL are in a good agreement with experimental data. The third part, a new approach for polytriarylamine (PTAA)-assisted selective dispersion for single-walled carbon nanotubes (SWNTs) in toluene solution has been developed. The triarylamine-based conjugated polymers are able to selectively wrap the SWNTs with specific chiral indices depending on their backbone structures (e.g., PTAA12, PTAA12-P and PTAA12-BP) and side-chain functionality (e.g., PTAA6, PTAA6-alt-PTAA and PTAA12-alt-PTAA). PTAA12 exhibits highly selective wrapping for the (6,5) chirality from CoMoCAT SWNTs but low selectivity in a dispersion of HiPCO SWNTs. Therefore, the selection for HiPCO SWNTs has been further improved via PTAA12-alt-PTAA wrapping with alternating side chains, which exhibits high affinity to (6,5), (7,5) and (9,8) chiralities. The limited conformations of PTAA12-alt-PTAA were due to incorporation of alternating side chains, which enhanced the selectivity of extraction of SWNTs. Finally, the saturated polynorbornene Poly(HNBOHPB) with a hexaphenylbenzene (HPB) moiety was prepared by ring-opening metathesis polymerization (ROMP) followed by hydrogenation. The nanographene-containing Poly(HNBOHBC) was prepared from Poly(HNBOHPB) via the Scholl reaction. The glass transition temperature of Poly(HNBOHPB) was 205 °C, and that of Poly(HNBOHBC) was higher than 300 °C. The temperatures required for a 10% weight loss (Td10) for Poly(HNBOHPB) and Poly(HNBOHBC) were 428 °C and 456 °C under a nitrogen flow, respectively, indicating the great improvement in thermal properties after the cyclodehydrogenation.The exfoliation of insoluble Poly(HNBOHBC) was prepared by bath sonication in CHP. The spectroscopic features of Poly(HNBOHBC) were investigated by UV-vis spectroscopy, fluorescence spectroscopy and photoluminescence excitation (PLE) mapping.