The influence of waste printed circuit boards characteristics and nonmetal surface energy regulation on flotation.

Improvement of the crushing effect of waste printed circuit boards by co-heating swelling with organic solvent

Design and synthesis of the hydrogen-bonded liquid crystalline (HBLC) mixtures are accomplished from diglycolic acid and 4-n-alkoxybenzoic acid (n = 9–12). Spectroscopic characterization such as UV...

Experimental and computational studies on induced thermochromic effect and re-entrant smectic phase in linear double hydrogen-bonded binary liquid crystal mixtures

Novel linear double hydrogen-bonded liquid crystals (HBLCs) were derived from diglycolic acid (DGA, a non-mesogenic compound) and 4-n-alkoxybenzoic acids (nOBA, n = 7 and 8 mesogenic compounds). Hydrogen bond (H bond) formation and its vibrational stretching frequencies had been calculated by experimental and theoretical IR spectroscopy. The calculated band gap energy (4.96 eV) using a UV-Vis spectrum clearly reveals the coincidence of highest occupied molecular orbital-lowest unoccupied molecular orbital band energy of the present HBLC mixture. Further, X-ray diffraction (XRD) studies at room temperature confirm the monoclinic nature of the HBLC mixture. Mesophases and their transition temperature were studied by a polarized optical microscope (POM) and differential scanning calorimetry (DSC). The order of the phase transition was evaluated by the thermal analysis. Due to the rotary motion of molecules, nematic phase (threaded texture) with thermochromic effect was observed. The induced thermochromism in the present HBLC and its possible color recording applications were discussed. Molecular descriptors (using computational density functional theory (DFT)) of the present mixture indicate the hardness and softness of the HBLC mixture. Natural bond orbital (NBO) studies revealed the O–H…O stabilization energy in the present HBLC mixture. Also, the lone pair (LP)-to-π* transition confirms the existence of intermolecular hydrogen bonding in the HBLC mixture. The calculated band gap energy of the DGA + nOBA HBLC mixture is a more useful parameter to identify suitable hydrogen-bonded liquid crystal material for photonic applications. Mulliken analysis shows clear evidence of the charge distribution in different molecules of the HBLC system.

Experimental and DFT Studies on Thermochromism Induced Binary HBLC Mixture

Detailed analysis of induced smectic phases and paramorphic effect of double hydrogen bonded ferroelectric liquid crystals

A new class of hydrogen bonded ferroelectric liquid crystals (HBFLC) have been designed and synthesized by intermolecular hydrogen bonds between mesogenic 4-decyloxybenzoic acid (10OBA) and non-mesogenic (R)-(+)-Methylsuccinic acid (MSA) which have been confirmed through experimental and theoretical studies. Further, Mulliken population analysis clearly reveals that the existence of hydrogen bonds, strength and dynamic properties. Textural observation and its corresponding enthalpy values are analyzed by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) respectively. Paramorphic changes in Sm C* phase due to the change of refractive index, which clearly reveal that the complex could be used for filtering action in photonic devices. The transition from lone pair to π* with large stabilization energy evidently exposes the chiral phases in the present HBFLC complex. Intermolecular interaction is analyzed by using natural bond orbital (NBO) studies. The highest energy in the HOMO-LUMO shows the stable phase in the HBFLC complex. Molecular structure of the HBFLC complex possesses the monoclinic which has been evinced through x-ray analysis. The randomly oriented bunch of homogeneous molecules in Sm A* phase of the HBFLC complex is reported.

Observation of paramorphic phenomenon and non-tilted orthogonal smectic phases in hydrogen bonded ferroelectric liquid crystals for photonic applications

D. Venugopal

Papers

Observation of paramorphic phenomenon and non-tilted orthogonal smectic phases in hydrogen bonded ferroelectric liquid crystals for photonic applications