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In this work, polymers of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-triphenylamine] with side chains containing: pyrene (C1), diphenyl (C2), naphthalene (C3), and isopropyl (C6) structures were synthesized via a Suzuki coupling reaction. The structures were verified using NMR and cyclic voltammetry measurements provide the HOMO and LUMO of the polymers. The polymer with pyrene (C1) and naphthalene (C3) produced photoluminescence in the green while the polymer with the side chain containing diphenyl (C2) and isopropyl (C6) produce dual emission peaks of blue-green photoluminescence (PL). In order to examine the electroluminescence properties of the polymers, the solutions were spin-coated onto patterned ITO anode, dried, and subsequently coated with an Al cathode layer to form pristine single layer polymer LEDs. The results are compared to a standard PFO sample. The electroluminescence spectra resemble the PL spectra for C1 and C3. The devices of C2, C3, and C6 exhibit voltage-dependent EL. An additional red emission peak was detected for C2 and C6, resulting in spectra with peaks at 435 nm, 490 nm, and 625 nm. The effects of the side chains on the spectral characteristics of the polymer are discussed.

We report stable and efficient quasi-solid-state dye-sensitized solar cells (QS-DSSCs) fabricated using a combination of TiO2 nanoparticles and a low-molecular-mass organogelator (LMOG) as a nanoparticle–gel composite electrolyte. Three types of electrolyte, namely liquid, LMOG-based gel, and nanoparticle–gel composite, are used. The results of electrochemical impedance spectroscopy and intensity-modulated photocurrent/photovoltage spectroscopy measurements suggest that the presence of TiO2 nanoparticles in the nanoparticle–gel composite electrolyte could afford faster electron transport and a longer electron recombination time compared to the liquid and LMOG-based gel electrolytes. The QS-DSSC using the nanoparticle–gel composite electrolyte with the optimal TiO2 content exhibits a power conversion efficiency of 7.79%, which is significantly higher than that of devices using the liquid (7.22%) and LMOG-based gel (7.21%) electrolytes. Remarkably, the QS-DSSCs with the optimal nanoparticle–gel composite electrolyte exhibit long-term stability over 10 days, unlike the liquid electrolyte-based cells.

A new approach for polytriarylamine (PTAA)-assisted selective dispersion for single-walled carbon nanotubes (SWNTs) in a 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 (catalytic processes) SWNTs but low selectivity in a dispersion of HiPCO (high-pressure carbon monoxide) SWNTs. Therefore, the selection for HiPCO SWNTs has been further improved via PTAA12-alt-PTAA wrapping with alternating side chains and mainly exhibits a high affinity to (6,5) SWNTs with high chiral angles (≥24.5°). The wrapping conformation and binding energy of the polymer/(6,5) SWNTs were studied via molecular modeling, and the simulated results are in good agreement with the experimental data for th...

In this study, a new triphenylamine-alt-fluorene conjugated copolymer, HPBPYFL6, with hexaphenylbenzene (HPB) and pyrene as asymmetrical pendant groups was synthesized via Suzuki coupling polymerization. The conjugated polymer had a weight-average molecular weight of 5.8 × 104 g mol−1 with a polydispersity index of 2.5 characterized by gel permeation chromatography (GPC). HPBPYFL6 showed good solubility in common organic solvents such as NMP, THF, toluene and dichloromethane at 25 °C. In addition, HPBPYFL6 possessed a high glass transition temperature of 260 °C and a 10% weight-loss temperature of 503 °C in nitrogen. HPBPYFL6 bearing a pyrene moiety had a solvatochromic fluorescence shift from a green to an orange emission as the polarity of the solvent increased. Cyclic voltammetry of HPBPYFL6 films cast onto indium-tin oxide-coated glass (ITO-glass) exhibited two oxidation redox couples at an E1/2 value of 0.82 and 1.17 V versus Ag/Ag+ in an acetonitrile solution. The HPBPYFL6 film on graphene-coated PET had an E1/2 value of 0.24 and 1.12 V. 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 switching and bleaching times were 5.16 s and 3.12 s for 1231 nm and were 3.30 s and 3.74 s for 1030 nm of HPBPYFL6 on ITO-glass. The strong NIR electrochromic absorbance of HPBPYFL6 was attributed to intervalence charge transfer by the incorporation of the HPB moiety. This phenomenon was confirmed by chemical oxidation as the oxidant contents increased in the solution state. Furthermore, the electrochromic mechanism was interpreted by DFT calculation and the simulated NIR electrochromic spectra of model compound HPBPYFL are in good agreement with the experimental data.

In this study we prepared a new class of pyrene-functionalized benzoxazines (Py-BZ) through reactions of phenol, paraformaldehyde, and pyren-1-amine (Py-NH2) in toluene and EtOH. We prepared Py-NH2 through catalytic reduction of 1-nitropyrene (Py-NO2), which we had synthesized through electrophilic aromatic substitution of pyrene, using HNO3 as the nitration agent. 1H and 13C nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy confirmed the chemical structure of this new monomer; differential scanning calorimetry (DSC) and FTIR spectroscopy revealed the curing behavior of the Py-BZ polymers. The presence of the pyrene-functionalized benzoxazine enhanced the solubility of single-walled carbon nanotubes (SWCNTs) in THF, leading to the formation of highly dispersible Py-BZ/SWCNT organic/inorganic hybrid complex materials. Fluorescence emission spectroscopy revealed significant π–π stacking interactions between the Py-BZ and the SWCNTs in these complexes. In addition, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis revealed that incorporating the SWCNTs into the Py-BZ matrix significantly enhanced the thermal stability of the polymer after thermal curing.

Novel conjugated polymers such as poly(phenylene-fluorene) P1 and poly(triphenylbenzene-fluorene) P2 with hexaphenylbenzene (HPB) as a pending side group were prepared by Suzuki coupling using the dibromo monomers M1 and M2 with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester, respectively. The HPB moiety of P1 and P2 can be oxidatively cyclodehydrogenated with FeCl3 in nitromethane, yielding polymers P3 and P4 with hexa-peri-hexabenzocoronene (i.e., nanographene) units. The cyclodehydrogenation of nanographene-containing polymers was confirmed by FT-IR spectroscopy. In addition, X-ray powder diffraction of both P3 and P4 revealed a polymer interlayer spacing of 1.3 nm being dominated by the nanographenes. The glass transition temperatures (Tgs) of P1 and P2 were 202 °C and 235 °C, respectively, while both P3 and P4 with nanographenes possessed Tgs higher than 300 °C. Compared to P3, P4 with a triphenylbenzene moiety in its backbone can be well dispersed without aggregation in N-cyclohexyl-2-pyrrolidone (CHP), as confirmed by UV-Vis spectroscopy, photoluminescence spectroscopy (PL) and photoluminescence-excitation (PLE) maps.

In this study, we synthesized a linear copolymer, poly(γ-propargyl-L-glutamate-graft-cyclodextrin) (PPLG-g-CD), through Huisgen [2 + 3] cycloadditions (click reactions) of monoazido-functionalized β-cyclodextrin (N3-CD) with the propargyl side chains, obtaining a self-assembling structure with a highly stable α-helical conformation and water-solubility. We used Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, wide-angle X-ray diffraction, and circular dichroism analyses in the solid state and in solution to characterize the transformations of the secondary structures between α-helix and β-sheet conformations. Temperature-dependent FTIR spectroscopic analyses revealed that the presence of the CD units on the PPLG side chain increased the stability of the α-helix conformation toward elevated temperatures, relative to that of pure PPLG. In addition, the presence of the CD cavities allowed the grafted polymers to form inclusion complexes with low-molecular-weight compounds, providing macromolecules with potential biomedical applications.