Papers by Keyword: Poly

Abstract: The characteristics of 3D cross-linking, mechanical properties and biocompatibility of new copolymers of polyetherurethane and polysiloxane are presented. New copolymers are shown to be highly durable, strong and stable, thus being prospective for various applications including biomedical implants.

Abstract: In recent decades, thermo sensitive polymer system has been intensively studied due to significant importance in fundamental studies and various applications. Methyl cellulose (MC) is a thermo sensitive natural polymer, having a phase transition temperature or a lower critical solution temperature of about 65 °C. When methacrylic acid (MAA) was added to the MC solution, the phase transition of MC occurred at a lower temperature less than 65°C, and a higher concentration of MAA leds to a lower phase transition temperature of MC. Based on the phase transition of MC solution triggered by MAA, the surfactant-free poly (methacrylic acid) nanogels were synthesized by using methyl cellulose as a template in an aqueous media. The resulting PMAA nanogels characterized by using dynamic light scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR). The nanogels of poly methyacrylic acid (PMAA) were affected by the concentration of both MC and MAA. A higher concentration of MAA led to a higher polymerization rate, and the higher concentration of MC resulted in the formation of the samller size of PMAA nanogels.

Abstract: Nanocomposite films of poly (9,9-dioctylfluorene) (PFO)/Al₂O₃ have been prepared by blending the conjugated polymer solution with alumina nanoparticle dispersion in common organic solvent and investigated in terms of the optical property. A blue shift of the photoluminescence (PL) spectrum for the as fabricated PFO/Al₂O₃ nanocomposite film was observed as compared to the results obtained from the bulk PFO film, the maximum of the PL emission peaks occurs at 442 nm in the bulk film while after the incorporation of the alumina nanoparticles the maximum appears at 420 nm in the spectrum for PFO/Al₂O₃ nanocomposite film. The dependence of fluorescence blue shift of PFO on the concentration of Al₂O₃ was investigated. The isolation of the conjugated polymer chains by the flat rafts of alumina nanoparticles was shown to play a key role for the obtained blue shift.

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: Conducting polymers poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-ethylenedithiathiophene) (PEDTT) have been synthesized by solid-state polymerization of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) and 2,5-dibromo-3,4-ethylenedithiathiophene (DBEDTT) respectively in air and under vacuum. Both polymers were completely insoluble in common organic solvents and retained partial crystal structure of monomers as indicated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Thermoelectric tests showed that PEDTT exhibited Seebeck coefficient about 120 µV K⁻¹ at 170 K, which is higher than PEDOT, while the later exhibited higher electrical conductivity (0.1S cm^-1 at 298 K) and better thermal stability indicated by the thermal analyses. These results showed that replacement of oxygen by sulfur in the monomer structure played an important role on the properties of polymers.