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The simple modification of the Schiff-base ligands often brings significant changes in the coordination properties of the metal-complexes, providing newer prospects for their unexplored applications. In this context, the present work utilized the “self-adaptable” acyclic diiminodipyrromethane Schiff's bases (2a and 2b) for the synthesis of their Zn-based complexes and explored their potential in the ring-opening polymerization of benzoxazines. The two zinc complexes of composition [Zn{(Ph)(CH3)C(2,6-iPr2C6H3–NCH–C4H2N)(2,6-iPr2C6H3–NCH–C4H2NH)}2] (3) and [ZnCl2{(Ph)(CH3)C(Ph3C–NHCH–C4H2N)2}] (4) were synthesized in good yields, and the structures were confirmed by single crystal X-ray diffraction (XRD). Later, zinc complexes (3 & 4) were used as catalysts to reduce the curing (ring-opening polymerization) temperature of benzoxazine monomers such as Bisphenol-A (BA-a) and Bisphenol-F (BF-a) benzoxazines. Dynamic scanning calorimetry (DSC) studies revealed that the on-set curing (Tp) temperatures were reasonably decreased upto 20% for the benzoxazines. Furthermore, the thermal stabilities of the polybenzoxazines (PBzs) derived in the presence of zinc catalysts (3 and 4) were compared with PBz obtained in the absence of catalyst under similar conditions. The thermal studies reveled that there is no significant changes in the initial degradation of polymers. However, the thermal stability in terms of char yields at 800 °C improved upto 10–21% for the bisphenol-A/F benzoxazines.

Structural defects, including point defects, dislocation and planar defects, significantly affect the physical and chemical properties of low-dimensional materials, such as layered compounds. In particular, inversion domain boundary is an intrinsic defect surrounded by a 60° grain boundary, which significantly influences electronic transport properties. We study atomic structures of the inversion domain grain boundaries (IDBs) in layered transition metal dichalcogenides (MoSe2 and MoS2) obtained by an exfoliation method, based on the aberration-corrected scanning transmission electron microscopy observation and density functional theory (DFT) calculation. The atomic-scale observation shows that the grain boundaries consist of two different types of 4-fold ring point shared and 8-fold ring edge shared chains. The results of DFT calculations indicate that the inversion domain grain boundary behaves as a metallic one-dimensional chain embedded in the semiconducting MoSe2 matrix with the occurrence of a new state within the band gap.

Highly ordered and three-dimensional (3-D) mesoporous carbon materials were prepared through a nano-hard templating approach using FDU-12 silica with tunable pore sizes as a template, which was synthesized via a microwave-assisted method. Powder XRD and microscopic techniques such as HR-TEM, HR-SEM, and N2 adsorption-desorption techniques were employed to characterize the structure and textural properties of the prepared mesoporous carbon samples. The characterization results reveal that all the mesoporous carbon samples show a 3-D porous mesostructure with tunable pore diameters (5.7 to 9.4 nm) and a large specific surface area in the range from 451 to 1251 m2 g−1. The super capacitive behavior of the cubic structured mesoporous carbons was determined using cyclic voltammetry, electrochemical impedance and charge-discharge measurements. The cubic mesoporous carbon materials exhibit a superior capacitive performance with a high specific capacitance value of 315.3 F g−1 at the current density of 1 A g−1, which is much higher than that of hexagonally-ordered mesoporous carbon with large pore diameters, activated carbon, and carbon nanotubes. The materials also show excellent cyclic stability and extremely low resistance. The superior specific capacitance of these materials is attributed to the combination of excellent surface properties such as large specific surface area, large pore volume and uniform pore diameter, spherical morphology, and a 3-D porous system with cage-type pores. Refereed/Peer-reviewed

In the present work, flexible, durable, transparent, conductive films (TCFs) were fabricated with the use of aqueous dispersed single-walled carbon nanotubes (SWCNTs). A small amount of the synthesized sulfonated poly(ether sulfone) (SPES) was used to effectively disperse SWCNTs with high aspect ratios. The lengths and heights of the dispersed SWCNTs were 2.5 ± 1.0 μm and 2 ± 1 nm, as determined by TEM and AFM, respectively. TCFs were fabricated using spray coating on a PET substrate; the best performance among the TCFs was achieved with a sheet resistance (Rs) of 125 Ω sq−1 and optical transmittance of 87.1%. Moreover, no appreciable change in the Rs was observed after repeated bending cycles and adhesive peel-off tests, which indicate that SPES acts as a good dispersant and effective binder for the improvement in durability and adhesion behavior of the resulting TCFs in the absence of additional binders. Therefore, this material holds great potential for scalable and facile production of flexible SWCNT-TCFs for various electronic applications.

Structural defects, including point defects, dislocation and planar defects, significantly affect the physical and chemical properties of low-dimensional materials, such as layered compounds. In particular, inversion domain boundary is an intrinsic defect surrounded by a 60° grain boundary, which significantly influences electronic transport properties. We study atomic structures of the inversion domain grain boundaries (IDBs) in layered transition metal dichalcogenides (MoSe

Nanocrystalline Li2CoSiO4 particles have been successfully synthesized via a supercritical fluid process. The as-synthesized and heated particles were 50-250 nm in diameter and were well dispersed as observed by high resolution transmission electron microscopy (HRTEM). Energy dispersive spectroscopy (EDS) and elemental mapping by scanning transmission electron microscopy (STEM) show the purity and homogenous elemental distribution of the Li2CoSiO4 particles. The high resolution transmission electron microscopy (HRTEM) images show well resolved lattice fringes of the crystalline Li2CoSiO4 particles. The structure of the Li2CoSiO4 particles has been determined for the first time by annular bright field-scanning transmission electron microscopy (ABF-STEM) and high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The results revealed a tetrahedral arrangement of CoSiO4 in the Li2CoSiO4 structure. The electrochemical performance results support the idea that this material has potential as a positive electrode for use in a lithium ion battery. Refereed/Peer-reviewed

In the present work, silica reinforced polybenzoxazine (PBZ–SiO2) hybrid materials possessing low surface free energy have been developed using a dimethylol-functional benzoxazine monomer (4HBA-BZ), tetraethoxysilane (TEOS) and 3-(isocyanatopropyl)triethoxysilane (ICPTS) through an in situ sol–gel process. Data from the contact angle measurement indicate that the hybrid materials are hydrophobic in nature and possess a low surface free energy. For example, a PBS3 hybrid material (1 : 1 : 1 ratio of 4HBA-BZ : ICPTS : TEOS) exhibits a low surface free energy of 18.6 mJ m−2 which is lower than that of poly(tetrafluoroethylene) (22.0 mJ m−2). Further data obtained from thermal studies indicate that the hybrid PBZ possesses higher values of the glass transition temperature (Tg), thermal stability and char yield than those of neat PBZ.

Degradation against atomic oxygen (AO), ultra-violet (UV) and vacuum ultra-violet (VUV) radiation has to be controlled in order to maintain the longevity and performance of light weight and high strength nanocomposites used in space and nuclear applications. With this in mind, a new synthetic route has been used to develop a semi-organic precursor, [polyhedral oligomeric silsesquioxane (POSS)] reinforced polybenzoxazine/epoxy (PBZ/EP) nanocomposites. PBZ/EP/POSS nanocomposites have been developed by reinforcing varying weight percentages of (0, 1.0, 3.0, and 5.0 wt%) POSS into 1 : 1 (w/w) ratio of BZ and DGEBA epoxy (EP) matrix via thermal curing. The developed nanocomposites were tested under UV irradiation at the wavelength of 365 nm for a period of one week. The values of tensile strength and morphological behaviour before and after exposure to UV irradiation have been determined in order to assess their radiation resistant behaviour. It was ascertained that the data obtained from the value of tensile strength for 5 wt% POSS reinforced PBZ/EP has changed only to an insignificant extent when compared to that of before UV irradiation. From SEM and XPS analysis, it was observed that a passive inert silica protective layer has been formed after radiation, which protects the composite materials from further deterioration due to radiation. Data from thermal and dielectric studies indicate that the POSS incorporated system possesses better thermal and low dielectric properties than those of the neat PBZ/EP matrix.

The present work addresses the synthesis of 1,4-bis(2-(4-hydroxyphenyl)-2-propyl)benzene based cyanate ester–silica hybrid (CE-SiO2) nanomaterials by an in situ sol–gel method. The nanomaterials are synthesized using a 1,4-bis(2-(4-cyanotophenyl)-2-propyl)benzene [CE] (organic phase) monomer and tetraethoxysilane (TEOS) (inorganic phase) in the presence of various molar ratios of coupling agents [γ-aminopropyltriethoxysilane (APTES) or 3-glycidoxypropyltrimethoxysilane (GPTMS)] through covalent bond interaction. The formation of a covalent bond between the organic and inorganic phases is confirmed by FT-IR. Thermal studies indicate that nanomaterials (CE–SiO2) show a higher Tg and thermal degradation temperature when compared with neat CE. Morphological studies confirm the molecular level dispersion of silica and CE resin. From the contact angle measurement, the hybrid materials are seen to possess better hydrophobicity i.e. the contact angle value increases from 89° and 57° to 108° and 78° for water and diiodomethane as a probe liquid respectively, also surface free energy reduced from 32.8 to 19.00 mJ m−2. These materials are expected to find wide application in the field of microelectronics and optoelectronics.