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Herein, we reported the first highly stable β-CD-based humidity sensor without the need of pre-functionalization of the QCM transducer surface. Two partially benzylated β-cyclodextrins (β-CDBn, x = 7 and 14) were prepared via a green and one-pot synthesis in aqueous media. The macromolecular structures were methodically investigated by means of NMR, FT-IR and MALDI-TOF spectroscopies and studied with DFT calculations. XRD analysis and thermal analysis revealed an amorphous morphology with better thermal stability in comparison with pristine β-CD. AFM characterization proved that the obtained water-insoluble cyclodextrin thin films exhibited good solution-processing characteristics and film-forming quality. Contact angle measurements evidenced a systematic increase in the surface hydrophobicity with the benzylation rate. These organic materials were investigated as sensitive membranes for humidity detection based on quartz crystal microbalance technique. The experimental investigation showed that the QCM coated with β-CDBn sensitive layer exhibited good sensing performances within a wide relative humidity range of 11-98% including high sensitivity, good linearity, fast response (15 s), desirable reproducibility and high stability even at high humidity level. [ABSTRACT FROM AUTHOR]

This study is an investigation about the effect of chemical modification on the morphological, optical and electrical properties of semiconducting organic thin films. Two confined poly( p-phenylene vinylene) (PPV)-type polymers containing different spacer groups were studied: P1 has an isopropylidene spacer group and P2 with hexafluoroisopropylidene spacer. The UV-Vis absorption and PL analysis showed a stronger π- π interaction in the P1 film; in P2, the π-stacking is limited by the introduction of a bulky trifluoromethyl (CF) groups on the spacer units. The P2 exhibits a better film quality as illustrated by the atomic force microscopy. The HOMO and LUMO energy levels and electrochemical band gap of the polymers were determinate by the cyclic voltammetry. The electrical properties of ITO/PPV derivative/Al diodes were investigated by means of current-voltage and show a space-charge-limited current conduction mechanism with higher mobility in the P2 thin layer. The impedance spectra of the devices can be discussed in terms of an equivalent circuit model designed as a parallel resistance ( R) and capacitance ( C) network in series with a resistance. [ABSTRACT FROM AUTHOR]

A new confined p-phenylenevinylene (PPV)-type polymer (BPAF-PPV) has been synthesized using Wittig condensation. The chemical structure of the polymer was well defined by 1H-NMR, 13C-NMR, and FT-IR spectroscopic analysis. BPAF-PPV contains oligomeric PPV units separated by hexafluoroisopropylidene groups in the main chain; it is fully soluble in common organic solvents and has a number-average molecular weight of 4570 g mol-1. Differential scanning calorimetry indicates that BPAF-PPV is amorphous and displays a glass transition temperature of 114 °C. The optical properties of the polymer were investigated by UV-visible absorption and photoluminescence spectroscopies. Its thin film showed a blue photoluminescence with a narrow emission spectrum. A high photoluminescence quantum efficiency of about 83% was determined in dilute solution. From the cyclic voltammetry analysis, the electrochemical bandgap was estimated to be 3.08 eV. A single-layer diode device of the configuration indium-tin oxide/BPAF-PPV/aluminium has been fabricated and has a relatively low turn-on voltage of 3.0 V. [ABSTRACT FROM AUTHOR]

Owing to exclusive thermal prospective of nanoparticles, diverse applications of such materials have been reported in heat transfer systems. The carbon nanotube (CNTs) is the modified class of nanoparticles which is preserve more stable thermal properties. The decomposition of CNTs with base materials offer special applications in enhancing thermal efficiency of energy systems, nuclear processes, sensors, diagnostic imaging etc. Following to such motivations in mind, the objective of current work is to present artificial neural network analysis for heat transfer problem due to suspension of carbon nanotubes-based nanofluid. Both single-walled and multi-walled carbon nanotubes are utilized to analyse the thermal impact of water base fluid. The source of flow is coaxially stretchable disks. The applications of porous medium phenomenon are reported to inspect the inertial effects. The problem is further updated by utilizing the radiative phenomenon, external heat generation and dissipation and slip constraints. The transport system is expressed via coupled nonlinear equations which are tackled via numerical computations. [ABSTRACT FROM AUTHOR]

The title compound, C(21)H(26)Cl(2)O(2), a bis-chloro-methyl derivative of O-ethyl-ated bis-phenol A, exhibits C(2) mol-ecular symmetry. It shows a bent conformation with the two benzene rings nearly perpendicular [dihedral angle = 87.17 (6)°].