10 research outputs found
Synthesis of imine-ester-linked benzothiazole mesogen containing liquid crystalline monomers with different terminal substituents
<p>A series of imine-ester-linked benzothiazole mesogen-based liquid crystalline (LC) monomers (<b>M1âM4</b>) having polymerizable methacrylate functional group as the terminal were designed and synthesized. These monomers were differentiated from each other by varying the terminal substituents (-H, -CH<sub>3</sub>, -OCH<sub>3</sub>, and -OCH<sub>2</sub>CH<sub>3</sub>) at the sixth position on the benzothiazole moiety. The chemical structures of the synthesized monomers were characterized and confirmed by spectroscopic techniques such as FTIR, <sup>1</sup>H NMR, and <sup>13</sup>C NMR. Thermogravimetric analysis (TGA) was used to study the thermal properties of the investigated monomers. The ethoxy substituted monomer (<b>M4</b>) showed higher thermal stability compared with the other monomers. The mesomorphic behavior of all the monomers was studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). DSC and POM studies revealed that the monomer (<b>M1</b>) having no substituent at the sixth position on the benzothiazole ring exhibited both smectic and nematic mesophases, whereas -CH<sub>3</sub>-, -OCH<sub>3</sub>-, and -OCH<sub>2</sub>CH<sub>3</sub>-substituted compounds revealed only nematic mesophase.</p
EDS elemental analysis of different points on the Si+C pellet.
<p>EDS elemental analysis of different points on the Si+C pellet.</p
The schematic illustrating: Si+C embedded centrifugal thermite and a compacted graphite crucible assembly charged with the loaded green mixture A: before reaction (left), B: after reaction (right) while subjected to centrifugal force, the front and behind side of Si-C pellet is identified after reaction.
<p>The schematic illustrating: Si+C embedded centrifugal thermite and a compacted graphite crucible assembly charged with the loaded green mixture A: before reaction (left), B: after reaction (right) while subjected to centrifugal force, the front and behind side of Si-C pellet is identified after reaction.</p
FESEM micrographs and EDS elemental analyses of a Si-C pellet removed from the tube of a centrifugal thermite-assisted reaction: (a) overall topography, (b), (c), and (d) microstructure of typical points; (e) and (f) high magnification of region (d).
<p>FESEM micrographs and EDS elemental analyses of a Si-C pellet removed from the tube of a centrifugal thermite-assisted reaction: (a) overall topography, (b), (c), and (d) microstructure of typical points; (e) and (f) high magnification of region (d).</p
Schematic representation of forces acting on a moving particle during the hybrid centrifugal SHS process.
<p>Schematic representation of forces acting on a moving particle during the hybrid centrifugal SHS process.</p
XRD patterns of the Silicon-Carbon pellet after being exposed to centrifugal SHS.
<p>XRD patterns of the Silicon-Carbon pellet after being exposed to centrifugal SHS.</p
The pyrometer temperature reading and calculated values of viscosity versus time during the hybrid SHS process; d = 1.00E-04 m, n = 58 RPS, Ï<sub>o</sub> = 7800 kgm<sup>-3</sup>, Ï<sub>m</sub> = 2700 kgm<sup>-3</sup>, R = 2.50E-02 m.
<p>Region (i) shows a sudden temperature decline immediately after the reaction started (point A to B), region (ii) temperature drops to the melting point of Fe the point B to C. At region (iii), (iv) the crucible temperature stays steady for 1.5 s around Fe melting point, the solidification of the molten Fe starts at point E.</p
The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials
<p>A series of azo-ester linked mesogen containing liquid crystalline acrylate compounds <b>C1-C6</b> having different terminal groups (âF, âCl, âBr, âOCH<sub>3</sub>, âOC<sub>2</sub>H<sub>5</sub> and âOC<sub>3</sub>H<sub>7</sub>) were successfully synthesised and characterised. The chemical structure, purity, thermal stability, mesophase behaviour and optical property of the synthesised compounds were investigated by different instrumental techniques. X-ray crystal structure showed that compounds <b>C1</b>, <b>C4</b> and <b>C5</b> exhibited more stable <i>E</i> configuration with two bulky group in the opposite side of the N=N double bond motifs. The fluoro-substituted derivative (<b>C1</b>) is connected by the R<sup>1</sup><sub>2</sub>(5) type of CâHâŠO hydrogen bond motifs whereas the molecules of <b>C4</b>, and <b>C5</b> are connected to each other by means cyclic R<sup>2</sup><sub>2</sub>(8) type of CâHâŠO hydrogen bond motifs. Thermogravimetric study revealed that the investigated compounds exhibited excellent thermal stability. All the compounds showed enantiotropic liquid crystal (LC) phase behaviour and the mesophase formation was greatly influenced by the terminal substituents. Alkoxy (âOCH<sub>3</sub>, âOC<sub>2</sub>H<sub>5</sub> and âOC<sub>3</sub>H<sub>7</sub>) substituted compounds exhibited greater mesophase stability than those of halogen (âF, âCl and âBr) terminated derivatives. UV-vis spectroscopic study revealed that the investigated compounds exhibited a broad absorption band around 300â420 nm with absorption maximum (<i>λ</i><sub>max</sub>) of nearly 370 nm.</p
Perovskite-Structured PbTiO<sub>3</sub> Thin Films Grown from a Single-Source Precursor
Perovskite-structured
lead titanate thin films have been grown on FTO-coated glass substrates
from a single-source heterometallic molecular complex, [PbTiÂ(ÎŒ<sub>2</sub>-O<sub>2</sub>CCF<sub>3</sub>)<sub>4</sub>(THF)<sub>3</sub>(ÎŒ<sub>3</sub>-O)]<sub>2</sub> (<b>1</b>), which was
isolated in quantitative yield from the reaction of tetraacetatoleadÂ(IV),
tetrabutoxytitaniumÂ(IV), and trifluoroacetic acid from a tetrahydrofuran
solution. Complex <b>1</b> has been characterized by physicochemical
methods such as melting point, microanalysis, FTIR, <sup>1</sup>H
and <sup>19</sup>F NMR, thermal analysis, and single-crystal X-ray
diffraction (XRD) analysis. Thin films of lead titanate having spherical
particles of various sizes have been grown from <b>1</b> by
aerosol-assisted chemical vapor deposition at 550 °C. The thin
films have been characterized by powder XRD, scanning electron microscopy,
and energy-dispersive X-ray analysis. An optical band gap of 3.69
eV has been estimated by UVâvisible spectrophotometry
Perovskite-Structured PbTiO<sub>3</sub> Thin Films Grown from a Single-Source Precursor
Perovskite-structured
lead titanate thin films have been grown on FTO-coated glass substrates
from a single-source heterometallic molecular complex, [PbTiÂ(ÎŒ<sub>2</sub>-O<sub>2</sub>CCF<sub>3</sub>)<sub>4</sub>(THF)<sub>3</sub>(ÎŒ<sub>3</sub>-O)]<sub>2</sub> (<b>1</b>), which was
isolated in quantitative yield from the reaction of tetraacetatoleadÂ(IV),
tetrabutoxytitaniumÂ(IV), and trifluoroacetic acid from a tetrahydrofuran
solution. Complex <b>1</b> has been characterized by physicochemical
methods such as melting point, microanalysis, FTIR, <sup>1</sup>H
and <sup>19</sup>F NMR, thermal analysis, and single-crystal X-ray
diffraction (XRD) analysis. Thin films of lead titanate having spherical
particles of various sizes have been grown from <b>1</b> by
aerosol-assisted chemical vapor deposition at 550 °C. The thin
films have been characterized by powder XRD, scanning electron microscopy,
and energy-dispersive X-ray analysis. An optical band gap of 3.69
eV has been estimated by UVâvisible spectrophotometry