Papers by Author: Ivana Moggio

Abstract: Oligo(phenylimines) hereafter named PI6, PI8 and PI9 were synthesized by condensation reaction between the terephtalaldehyde and diamines of different length size (diaminohexane, diaminooctane and diaminononane) via mechanochemistry. The reactions were carried out without solvent or catalyst and completed after only 90 minutes. The products were characterized by ¹H-NMR, UV-Vis, FT-IR spectroscopy, GPC, DSC and Small angle X-ray diffraction. Thin films were prepared by spin coating from concentrated solutions on glass and quartz substrates and mechanically rubbed with a polyacrylonitrile tissue. The oriented films were studied by both Laser Scanning Confocal Microscopy (LSCM) and UV-Vis spectroscopy. With this last technique, the higher optical dichroism was observed for PI6. The oriented films of this oligo(phenylimine) were thus used as patterns to induce molecular orientation of a fluorescent phenyleneethynylene polymer in order to obtain polarized light emission.

Abstract: In this paper, we studied the influence of the silver nanoparticles size on the electrical conductivity of PEDOT:PSS in Ag(PEDOT:PSS) films. The silver nanoparticles were synthesized in presence of PEDOT:PSS by varying the molar ratio between AgNO3 and the reducing agent (NaBH4). Both the particle size determined by TEM and the plasmon band obtained by UV-Vis spectroscopy were found to be strongly dependent on the reducing agent concentration. The electrical conductivity increases inversely with the concentration of reducing agent from 5.24 x 10-4 up to 1.63 S/cm; three orders of magnitude higher than pristine PEDOT:PSS.

Abstract: Bromobenzenethiol passivated gold nanoparticles were mixed with a poly(phenylene ethynylene) bearing thioester flexible sequences in order to obtain a fluorescent composite for optical biosensors. The particles and the composite were characterized by 1H, 13C NMR, UV-Vis and fluorescence spectroscopy, TEM and STEM. The particles are homogeneously dispersed in the polymer matrix as observed by electron microscopy. The NMR spectra suggest that the gold particles and the poly(phenylene ethynylene) are probably interacting through the sulfur atoms of the –C(O)S- and –CH2-S-CH2- moieties of the flexible sequences of the polymer as well as through  interactions between the aromatic ring of 4-bromobenzenthiol and the conjugated backbone of pPET3OC12-sqS. The quantum yield of the composite both in solution and in solid state films is slightly lower than that of pPET3OC12-sqS because of the quenching effect of gold. Nonetheless, a change of the fluorescence intensity of the composite films can be detected as a consequence of the contact with microorganisms. Preliminary microbiological assays indicate an antimicrobial effect of the composite film with the E. coli bacteria.