Steam explosion technique was used to isolate banana fibrils from banana fiber. The surface polarity of banana fiber, banana fibril, and chemically-treated banana fibril was investigated by ultraviolet/visible spectroscopy using solvatochromic probe dye molecules. The empirical Kamlet-Taft solvatochromic polarity parameters such as hydrogen bond donating ability HBD (alpha), hydrogen bond accepting ability HBA (beta), the dipolarity (pi*), Gutman acceptor number, and Reichardts ET(30) values for the banana fiber, banana fibril, and chemically-treated banana fibril were determined. It was observed that banana fibril has higher HBD value than banana fiber. Chemical treatment of the banana fibril has lowered the HBD value. The results of the empirical polarity parameters determined were found to be consistent with the results of electrokinetic measurements. The functional groups on the surface of banana fiber, banana fibril, and chemically-treated banana fibril was further analyzed using Fourier transform infrared spectroscopy (FTIR). FTIR spectra revealed the dissolution of the various components from the banana fiber after steam explosion which was further confirmed by scanning electron microscopy.
A readily synthetic route to endow the surface of hydrophobic carbon black (CB) particles with primary amino groups has been developed. The adsorption of the water-borne polyelectrolyte copolymer poly(vinyl amine-co-vinyl amide) (PVAm) on CB was studied as function of pH and polyelectrolyte concentration. The amino-functionalization process of CB with PVAm strongly depends on pH. As shown by electrokinetic measurement as function of pH, the content of accessible primary amino groups on the surface of CB increases with increasing the OH- concentration. The alternative functionalization of the CB surface with an anionic polyelectrolyte is demonstrated for the adsorption of poly(ethylene-alt-maleic anhydride) (PEMSA). About 50 mg of PVAm can be adsorbed on 1.0 g of CB, which is sufficient to completely alter the surface net charge. The aim of the introduced functional amino groups is their ability to act as anchoring groups for subsequent surface reactions improving the CB's process ability, compatibility, and adhesion properties.
Due to their unique technical properties, the importance of semiconductor nanocrystal quantum dots (QDs) increased over the last decades especially for the use of quantum dot light-emitting diodes (QD-LED) [1,2] or detectors [3]. In present QD-LED arrangements, layer stacks e.g. hole injection layer (HIL), hole transport layer (HTL), QD layer (QDL), hole blocking layer (HBL), and electron transport layer (ETL) are mostly formed by two or more process steps including spin-coating, thermal deposition or vapor deposition. The latter in general is used for assembling the ETL, because the QDs active matrix group (ligands) is unstable for organic solvents. Nevertheless a reduction of process steps and thus decreasing material consumption could be an advance in manufacturing QD-LEDs. Therefore we discuss the fabrication of an all-spin-coated CdSe/ZnS core shell type QD-LED only consisting of HIL, QDL, and ETL showing electroluminescence at 610 nm. Thereby the used ETL addition ally fulfils the function as HBL. Although the ETL has high electron mobility, the QD-LEDs conductivity was improved further through thermal annealing steps while fabrication
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