The properties of isomeric azulene derivatives based on 7- versus 5-membered ring substitution were examined by the synthesis and characterization of well-defined electroactive oligomers. The substitution pattern was shown to dramatically influence solid-state, electronic and optical properties of the oligomers with acid-responsive materials only being observed when the azulenium cation could be directly stabilized by substituents in the 7-membered ring. Protonation was accompanied by a reversible color change and a strong red-shift of the absorption maximum as indicated by UV-vis studies. In addition, we show that the absorption maxima and optical band-gaps of azulenium cations can be tuned by the nature of the chromophore connected to the seven-membered ring of the azulene nucleus.

The development of efficient synthetic strategies for incorporating antibacterial coatings into textiles for pharma and medical applications is of great interest. This paper describes the preparation of functional nonwoven fabrics coated with polyaniline (PANI) via in situ polymerization of aniline in aqueous solution. The effect of three different monomer concentrations on the level of polyaniline coating on the fibers comprising the fabrics, and its electrical resistivities and antibacterial attributes, were studied. Experimental results indicated that weight gains of 0.7 and 3.0 mg/cm² of PANI were achieved. These levels of coatings led to the reduction of both volume and surface resistivities by several orders of magnitude for PANI-coated polyester-viscose fabrics, i.e., from 10⁸ to 10⁵ (Ω/cm) and from 10⁹ to 10⁵ Ω/square, respectively. Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM) confirmed the incorporation of PANI coating with an average thickness of 0.4–1.5 µm, while Thermogravimetric Analysis (TGA) demonstrated the preservation of the thermal stability of the pristine fabrics. The unique molecular structure of PANI, consisting of quaternary ammonium ions under acidic conditions, yielded an antibacterial effect in the modified fabrics. The results revealed that all types of PANI-coated fabrics totally killed S. aureus bacteria, while PANI-coated viscose fabrics also demonstrated 100% elimination of S. epidermidis bacteria. In addition, PANI-coated, PET-viscose and PET fabrics showed 2.5 log and 5.5 log reductions against S. epidermidis, respectively.

A statistical copolymer containing thiophene and thiophene dioxide, namely poly[(3-hexylthiophene)-co-(3-hexylthiophene-S,S-dioxide)] (P3HT-TDO), was utilized as a thermal crosslinker in a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₀-butyric methyl ester (PCBM), demonstrating an effective strategy for preventing agglomeration of PCBM and enhancing blend stability. P3HT-TDO was synthesized by microwave-assisted oxidation of P3HT and its characterization was carried out using UV-Vis spectroscopy, ¹H-NMR, Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Crosslinking of P3HT-TDO was achieved via Diels–Alder reaction at ∼150 °C. Thermogravimetric analysis, combined with FTIR and differential scanning calorimetry, were used to study the crosslinking process. In order to test the impact of thermal cross-linking, field effect transistors (FETs) were fabricated using pristine and compared to cross-linked P3HT. It was found that P3HT-TDO crosslinking did not suppress charge mobility. The stability of the P3HT/P3HT-TDO/PCBM blend was characterized in the solid-state from spin-coated thin films. The samples were analysed using UV-vis spectroscopy and Grazing Incidence X-ray Diffraction (GIXRD) to monitor the effects of thermal processing. The results revealed that presence of P3HT-TDO in the blend minimizes crystallization of PCBM during annealing and preserves the ordered microcrystalline segments from P3HT. Optical microscopy analysis of P3HT/P3HT-TDO/PCBM thin films also confirmed the effectiveness of the strategy and inhibition of PCBM crystal formation even after 155 hours of annealing.