E. Bhoje Gowd

Transition-metal-based layered double hydroxides tailored for energy conversion and storage

Currently, energy storage devices draw considerable attention owing to the growing need for clean energy. The depletion of fossil fuels and the generation of greenhouse gases have led to the development of alternative, environmentally friendly energy storage devices. Supercapacitors with high power densities are excellent devices for energy storage. Although carbon-based materials are widely used in such devices, their non-faradic behavior in electrical double layer capacitors (EDLCs) limits the maximum power density that can be generated. In contrast, the faradaic mechanism of transition metal hydroxides results in better capacitance rates along with good stability during cycling. This review is confined to nickel cobalt layered double hydroxides (NiCo LDHs) classified based on the fabrication of electrodes for application in supercapacitors. We discuss the growth of the active LDH material in situ or ex situ on the current collector and how the synthesis can affect the crystal structure as well as the electrochemical performance of the electrode.

Aerogels of hierarchically porous syndiotactic polystyrene with a dielectric constant near to air

Herein ultralow density aerogels are developed through a feasible freeze casting technique. Briefly, the syndiotactic polystyrene (sPS) gel was prepared using xylene and subjected to successive steps of solvent exchange using non-solvents like ethanol and water. These samples were freeze-dried to obtain aerogels of the same shape and size as gels. The aerogels obtained exhibited the lowest ever dielectric constant of any polymer aerogel (κ = 1.03 ± 0.02), which is very close to that of air. Moreover, while analyzing the crystal structure, it was observed that the water derived sPS aerogel existed in the empty δ (δe) form, with microcavities in the crystal lattice in addition to meso and macroporosity. However, annealing at different temperatures yielded aerogels with different polymorphic forms without microporosity leading to slight variations in the dielectric constant. The microporosity in the crystalline state along with the lower density of the material were proven to be the major contributing factors to the lowest ever reported dielectric constant of the sPS aerogel. The sPS aerogels with an ultra low dielectric constant, very high hydrophobicity and adequate mechanical strength can stand as an alternative to conventional brittle inorganic aerogels.

Nanostructures Based on Self-Assembly of Block Copolymers

Block copolymers have attracted increasing interest for the synthesis of nanomaterials and fabrication of nanostructures due to their ability to self-organize at nanometer scales. A variety of nanoscale morphologies can be obtained by controlling the composition and architecture of the individual block components. In this chapter, we highlight the recent advances in the formation of nanostructures in bulk, generation of block copolymer based nanotemplate ordered thin films and their potential applications in nanofabrication including template nanolithography, deposition of functional nanomaterials as well as nanoporous membranes.

A high-performance BaTiO3-grafted-GO-laden poly(ethylene oxide)-based membrane as an electrolyte for all-solid lithium-batteries

Nanocomposite polymer electrolytes (NCPEs) comprising poly(ethylene oxide) (PEO), barium titanate-grafted-graphene oxide (BaTiO3-g-GO) and lithium bis(trifluoromethanesulfonyl imide) (LiTFSI) were prepared by a simple hot-press technique. An increase of two orders of magnitude in the ionic conductivity was achieved upon incorporation of BaTiO3-g-GO in the polymeric matrix even at 0 °C. The addition of BaTiO3-g-GO as a filler has significantly enhanced the thermal stability and mechanical integrity of the membrane. The BaTiO3-g-GO-laden membrane was found to have better interfacial properties with a lithium metal anode than the filler-free membrane. Charge–discharge studies revealed a stable cycling profile even at 5C-rate and it was found to be superior to those reported earlier.

Crystallization and Polymorphic Behavior of Nylon-Clay Nanocomposites

Nylons are very successful semicrystalline polymers and are commercially exploited extensively. The incorporation of nano-sized layered silicates into nylons has a significant influence on the crystallization behavior, polymorphism, and hence on the properties of the polymers. In this chapter, we highlight the preparation of nylon nanocomposites by various methods and the effect of layered silicates on the crystallization, crystallization kinetics, crystal structure, and polymorphic transitions in nylon–clay nanocomposites.

Crystallization Behavior of Crystalline–Amorphous and Crystalline–Crystalline Block Copolymers Containing Poly(l-lactide)

Abstract Block copolymers containing biodegradable blocks become increasingly important in material science because of their potential applications in several areas, ranging from highly selective separation membranes to biomedical devices. Particularly, the incorporation of the semicrystalline block such as poly( l -lactide) (PLLA) in block copolymers leads to the formation of unique morphologies because of the competition between microphase separation and crystallization of PLLA. In this chapter, we highlight the advances in the structure and morphology development in semicrystalline block copolymers containing PLLA blocks. Understanding the structural evolution and the formation of the final morphology of these block copolymers is of major interest because it is in direct relationship with the properties and performance of these materials.

Ultrasonic-Assisted Electroless Coating of Ni-B Alloy and Composites on Aluminum Alloy Substrates

Electroless nickel coating is one of the versatile methods to improve the physical properties of aluminium alloys. The increasing demand for high corrosion resistant surface with improved performance leads to the development of poly-alloy and composite coatings with the aid of ultrasonication. In the present study Ni-B alloy and Ni-B-CeO2 composite coatings were made on 356 aluminium alloy surfaces. The variation in structural and mechanical properties of coatings formed under both ultrasonication and magnetic stirring were investigated. Surface analysis by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) has shown the formation of more uniform coating under ultrasonication. The electrochemical polarization tests show enhanced corrosion resistance in ultrasonic assisted coatings.