Behavior of some wool fabrics as such or functionalized with semiconductor nanoparticles against the photodegradation of Rhodamine B was investigated. The wool samples were commercially purchased, they were chosen to differ by the chemical nature of the yarns, by the size of the 2D texture elements and by the applied pretreatment. The samples were routinely characterized both in the original form and in the form coated with the oxide particles as well to consider the structure, the surface morphology and their changes due to dye deposition. Several techniques were routinely applied: optical microscopy, XRD, SEM, TGA, UV-Vis spectroscopy and FTIR-ATR. Data have shown that TiO2 layer has either an amorphous structure or is highly dispersed. Drops of Rhodamine B solution were deposited by sessile drop method. We have obtained optical images of the wet/colored spot during the radial wicking, collected with a usual camera. Image comparison was made by direct visualisation. The optical images of the spot on fabrics were taken immediately after the dye was applied, after the fabric was dried and afterwards, after the system illumination by UV-vis light as function of the time. The obtained final spots speak about the dye photodegradation in the studied cases.
Polymer Dispersed Liquid Crystal (PDLC) films are composite materials consisting of LC droplets embedded in polymers. In order to decrease the switching voltage of these devices, we prepared PDLC films doped with single wall carbon nanotubes (SWCNTs). The mesomorphic properties of the films were investigated by polarizing optical microscopy (POM). The electrical characteristics have been investigated using a Broadband Dielectric Spectrometer in a frequency domain (0.01-107) Hz and a temperature range (280-350) K. Some key aspects of an optical model for the analysis of the coherent transmittance of PDLC - NP films are presented.
Novel lanthanidomesogens based on lanthanide nitrates carrying three 4-pyridone ligands having two alkoxy chains at the periphery were synthesized and their structure was assigned based on IR spectroscopy and elemental analysis. Their thermal stability was evaluated by TG analysis confirming that the decomposition starts at very high temperatures around 300°C. The liquid crystalline properties were investigated by using a combination of techniques: polarized optical microscopy (POM) and differential scanning calorimetry (DSC) and, for selected compounds, by variable-temperature powder X-ray diffraction. The new liquid crystal display a hexagonal columnar phase (Colh) between 63°C and 242°C, depending on the length of the alkyl chain. Dielectric spectroscopy on a wide frequency range was used to evaluate the dipolar relaxation processes. The emission properties of a mixture of E7 doped with a selected europium complex filled in a planar cell were investigated on changing the applied voltage, ranging from 0V up to 15V.
Polymer Dispersed Liquid Crystals (PDLC) are composite materials consisting of small liquid crystal (LC) droplets surrounded by a polymer matrix. Due to their relatively easy preparation and processing, the PDLC devices found many applications such as displays, architectural windows, energy control devices, projection displays, spatial light modulators, polarizers.
Carbon nanotubes (CNT) have excellent mobility and are suitable as doping nanoparticles in order to improve the electrically- controlled orientation of LC.
This paper presents the methods of preparation of PDLC doped with CNT. Experimental results are presented for the films obtained by solvent induced polymerization method, using polymethyl methacrylate and a nematic LC, E7. The obtained films are characterized by polarized optical microscopy, differential scanning calorimetry and electro-optical transmission.
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