Novel hydrazone based polymers as hole transporting materials

The novel family of hole transporting polymers containing hydrazone moieties is reported. The polymers were prepared in polyaddition reaction of hydrazone-containing diepoxydes with 4,4′-thiobisbenzenethiol in the presence of catalyst triethylamine (TEA). Obtained polymers were found to constitute novel polymeric hole transporting materials (TM) characterized by differential scanning calorimetry and time of flight method. The highest hole drift mobility in the newly synthesized polymers exceed 10⁻⁴ cm² V⁻¹ s⁻¹ at an electric field of 10⁶ V cm⁻¹ was observed in the TM with triphenylamine moieties.     

Synthesis of the hole-transporting molecular glasses possessing pendant 3,6-dibromocarbazolyl moieties

Synthesis and properties of the well-defined 3,6-dibromocarbazolyl-containing molecular glasses are reported. They were prepared by the nucleophilic opening of the oxirane ring of 1,3-di(3,6-dibromocarbazol-9-yl)-2-propanol glycidyl ether with aniline, 4-fluoro-, 4-bromoanilines, 2,5-dimercapto-1,3,4-thiadiazole or glycidyl ether of 1,3-di(carbazol-9-yl)-2-propanol with 4,4′-thiobisbenzenethiol and 1,9-nonanedithiol followed by bromination. The obtained materials were examined by various techniques including differential scanning calorimetry, NMR, MS, UV, PL spectrometry. The electrophotographic parameters of the molecular glasses doped with difluoroboron-1,3-bis(4-metoxyphenyl)-1,3-propanedionate have been studied. The electrochemical properties and ionization potentials, measured by electron photoemission method in air, were investigated.     

Backward-wave-oscillator spectrometry in standards and material characterization

Tunable backward-wave oscillators (BWO) equipped with computer aided control and data processing means are applied for liquid (e.g. mineral oil) and solid (Si, GaAs, YBaCuO) sample spectrometry in the frequency range above 200 GHz.     

Hydrothermal carbonization of distiller’s grains

Wet distiller’s grains are intermediate byproducts of ethanol manufacture that have high moisture contents and require significant energy for drying and conversion into dry distiller’s grains. Hydrothermal carbonization was investigated as a wet process to provide alternative products, and chars were obtained in moderate yield that possessed high heats of combustion. The mechanism of char formation was also investigated employing constituent materials representative of the chemical composition of distiller’s grains. Char formation was discovered to chiefly involve carbohydrates (other than cellulose) and proteins. A surprising discovery was that triacylglycerides and fatty acids created under the reaction conditions did not contribute to char yield and were adsorbed onto the chars and could be easily extracted.     

Solution processable C60 fullerene-hydrazone dyads for optoelectronics

Ambipolar, narrow band gap (∼1.35 eV) fullerene-arylhydrazone dyads have been synthesized utilizing the Prato-Maggini-Scorrano reaction followed by the condensation with phenylhydrazines. Room temperature electron and hole mobilities, measured by the xerographic time of flight technique, exceed 10⁻⁴ cm² V⁻¹ s⁻¹ at strong electric fields. The values of ionization potential, measured by the photoemission in air method, are in the range of 5.29–5.36 eV. Good ambipolar charge transport, photosensitivity across the whole visible light region of the spectrum, and solubility in common organic solvents makes these dyads attractive materials for various optoelectronic applications.     

Carbazole-containing enamines as charge transport materials for electrophotography

Synthesis and thermal, optical as well as photoelectrical properties of carbazole-based enamines are reported. The synthesized compounds were found to form glasses with the glass transition temperatures up to 104 °C as characterized by differential scanning calorimetry. Electron photoemission spectra of the synthesized enamines have been recorded and the ionization potentials have been established. The lowest value of ionization potential (5.22 eV) and the best charge transport properties were shown by di(2,2-diphenylvinyl)(9-ethyl-3-carbazolyl)amine. Room temperature hole-drift mobilities in its 50% solid solutions in bisphenol Z polycarbonate established by the xerographic time-of-flight technique were found to be 9 × 10⁻⁵ cm² V⁻¹ s⁻¹ at electric field of 10⁶ V cm⁻¹.     

Molecular glasses possessing a phenyl-1,2,3,4-tetrahydroquinoline moiety as hole transporting materials for electrophotography

The new hole transporting materials which comprise molecules consisting of two hydrazone branches linked with flexible thiobiphenyl or thiophenyl sulphide and two hydroxyl groups containing central bridge were synthesized and investigated. These transporting materials possessing phenyl-1,2,3,4-tetrahydroquinoline moieties are low molecular glasses and allow preparing stable to crystallization layers. The ionization potentials of these compounds are ca. 5.3 eV as determined by the electron photoemission method. These low molecular glasses can be used as hole transporting materials with or, in the case of a solid substrate, without binder polymer. The hole drift mobility of the newly synthesized compounds, measured by xerographic time of flight method, exceeds 10⁻⁵ cm²/V s at an electric field of 10⁶ V/cm.     

Hydrothermal carbonization of microalgae

Hydrothermal carbonization is a process in which biomass is heated in water under pressure to create a char product. With higher plants, the chemistry of the process derives primarily from lignin, cellulose and hemicellulose components. In contrast, green and blue-green microalgae are not lignocellulosic in composition, and the chemistry is entirely different, involving proteins, lipids and carbohydrates (generally not cellulose). Employing relatively moderate conditions of temperature (ca. 200 °C), time (<1 h) and pressure (<2 MPa), microalgae can be converted in an energy efficient manner into an algal char product that is of bituminous coal quality. Potential uses for the product include creation of synthesis gas and conversion into industrial chemicals and gasoline; application as a soil nutrient amendment; and as a carbon neutral supplement to natural coal for generation of electrical power.     

Multifunctional emissive material based on 1-phenyl-1,2,3,4-tetrahydroquinoline

A novel compound based on 3-hydroxy-1-phenyl-1,2,3,4-tetrahydroquinoline and electron affinitive cyano moieties incorporated into the bis(styryl) molecular structure was investigated as a potential multifunctional emissive material. The ionization potential and the LUMO level of the compound were estimated to be 5.66 eV and 3.2 eV, respectively. The hole drift mobility (5 × 10^?5 cm²/V s) of a vacuum-deposited thin film evaluated using time-of-flight was independent of the electric field. Moreover, the fluorescence and electroluminescence spectra of vacuum-deposited film demonstrated good coincidence and both displayed almost pure yellow-green emission color.     

Hydrothermal carbonization of microalgae II. Fatty acid,char, and algal nutrient products

A process for isolation of three products (fatty acids, chars and nutrient-rich aqueous phases) from the hydrothermal carbonization of microalgae is described. Fatty acid products derived from hydrolysis of fatty acid ester groups in the microalgae were obtained in high yield and were found to be principally adsorbed onto the char also created in the process. With the highest lipid-containing microalga investigated, 92% of the fatty acids isolated were obtained by solvent extraction of the char product, with the remaining 8% obtained by extraction of the acidified filtrate. Obtaining the fatty acids principally by a solid–liquid extraction eliminates potential emulsification and phase separation problems commonly encountered in liquid–liquid extractions. The aqueous phase was investigated as a nutrient amendment to algal growth media, and a 20-fold dilution of the concentrate supported algal growth to a level of about half that of the optimal nutrient growth medium. Uses for the extracted char other than as a solid fuel are also discussed. Results of these studies indicate that fatty acids derived from hydrothermal carbonization of microalgae hold great promise for the production of liquid biofuels.