Organic semiconductor based gas sensors have several advantages over their inorganic counterparts. However, despite the advantages organic gas sensors are far behind the inorganic ones in terms of applicability mainly due to lack of understanding of the fundamental processes involved. Hence, to understand the gas sensing mechanism in chemiresistor and transistor based organic sensors more deeply and to achieve better performances, it is essential to establish a relationship between device performance and intrinsic charge transport properties of an organic semiconductor (OSC) which is fundamentally different from the usual inorganic ones. In this work, we therefore designed a small organic molecule with push−pull architecture, trans-4-nitro-4′-dimethylamino-α-aminostilbene (NNDMNH 2 ), which has been predicted to have one-dimensional (1D) π−π stacking of molecules, and we used it as a model nanowire to study the correlation between the sensing mechanism and basic structural and charge transport parameters. Our work shows how possibly the modulation of the coupling matrix element, one of the basic charge transport parameters, due to the change in molecular geometry during adsorption of gas molecules (nonlocal electron−phonon coupling), can decrease the intrinsic mobility and ultimately affect the sensing performance of the device. The difference in the gas sensing mechanisms of an OSC and its inorganic counterpart can be well understood from our study. On the basis of our findings we propose a materials design principle which shall help to achieve better performance in future. We also find NNDMNH 2 as a potential sensor of oxidizing SO x (x = 2, 3) gases, which is important because OSC based gas sensors are still far behind from their inorganic counterparts in sensing of oxidizing gases.

An ionic liquid (IL) is a salt that consists of a cation and an anion, one of which possesses an organic component. Because of the non-volatile property, these solvents have a high recovery, and hence they are considered as environment-friendly green solvents. It is necessary to study the detailed physicochemical properties of these liquids for designing and processing techniques and find suitable operating conditions for IL-based systems. In the present work, the flow behavior of aqueous solutions of an imidazolium-based IL, 1-methyl-3-octylimidazolium chloride ([OMIM][Cl]), is investigated where the dynamic viscosity measurements indicate a non-Newtonian shear thickening behavior in the solutions. Polarizing optical microscopy shows the pristine samples to be isotropic that transforms into anisotropic after shear. This shear thickened liquid crystalline samples change into an isotropic phase upon heating which is quantified by the differential scanning calorimetry. The small angle X-ray scattering study revealed the pristine isotropic cubic phase of spherical micelles to distort into a non-spherical micelles. This has provided the detailed structural evolution of mesoscopic aggregates of the IL in an aqueous solution and the corresponding viscoelastic property of the solution.

Ionic liquids (ILs) are organic salts with a low melting point compared to any inorganic salts. The room temperature ILs are of great importance for their widespread potential industrial applications....

Hamiltonians that are multivalued functions of momenta are of topical interest since they correspond to the Lagrangians containing higher-degree time derivatives. Incidentally, such classes of branched Hamiltonians lead to certain not too well understood ambiguities in the procedure of quantization. Within this framework, we pick up a model that samples the latter ambiguities and simultaneously turns out to be amenable to a transparent analytic and perturbative treatment.

Dissipative particle dynamics (DPD) simulations has been performed to study the phase transition of a mixture of cationic and anionic surfactants in an aqueous solution as a function of the total concentration in water and the relative ratio of surfactants. The impact of the relative difference between the tail lengths of the cationic and anionic surfactants on the phase diagram has been simulated by tuning the number of DPD beads in the simulation model. This research also discusses the impact of the frequently used values of the parameters associated with the harmonic bonds among the bonded DPD beads on the obtained self-assemblies. We find remarkable differences in the resultant self-assemblies based on different choices of harmonic bond parameters. The performed simulations show an enhanced spectrum of self-assemblies with augmented tail lengths and disparate harmonic bond parameters. The obtained self-assemblies are quite unique and can potentially be used in the future for various applications. We also compare the simulation results of the vesicle structures obtained by modeling the electrostatic interaction in the simulation among the charged beads by explicitly introducing charges with a long-range interaction with those obtained by tuning the implicit electrostatic interaction without the long-range interaction. The effects of the chain length of the model and the harmonic bond parameters on the internal density of DPD beads and stress profiles within the vesicles are examined closely. These results are a significant contribution to understanding the stability of the phases and tailoring of the desired vesicles.