Bhaskar Jyoti Saikia

Designing hierarchical NiO/PAni-MWCNT core–shell nanocomposites for high performance super capacitor electrodes

A novel type of nanocomposite material based on multi walled carbon nanotubes (MWCNT) and NiO nanoparticles coated with polyaniline (PAni) has been prepared by an in situ polymerization technique. Transmission electron microscopy confirms the core–shell structure of the composite. TG-analysis reveals that NiO/PAni-MWCNT nanocomposites exhibit better thermal stability than NiO-PAni. The synthesized nanocomposites have good conductivity and excellent electrochemical properties. The specific capacitance values of these composites were measured from their galvanostatic charge–discharge curves. The particles show a high value of specific capacitance and can find potential application as super capacitor electrodes.

Preparation and characterization of an azide–alkyne cycloaddition based self-healing system via a semiencapsulation method

An azide–alkyne cycloaddition based self-healing system was designed by a semiencapsulation method. Multiwall carbon nanotubes were functionalized with poly(t-butyl acrylate) containing azide end functionality using atom transfer radical polymerization. Subsequently the alkyne counterpart was encapsulated in urea formaldehyde microcapsules and embedded in an epoxy matrix. The healing click reaction was triggered by an embedded copper catalyst. Whenever a damaging event occurs in the epoxy matrix, the liquid cross linker in the presence of catalyst will dissolve the implanted catalyst from the matrix initiating the crosslinking reaction between azide and alkyne and thus healing the cracks. The effects of temperature and healing duration on healing efficiency are investigated. Once healed, the self-healing system recovers as much as 65% of its original fracture toughness.

Designing Self-Healing Polymers by Atom Transfer Radical Polymerization and Click Chemistry

The development of smart self-healing polymeric materials and composites has been the subject of a tremendous amount of research over last few years. When self-healing materials are mechanically damaged, either internally (via crack formation) or externally (by scratching), they have the ability of restoring their original strength and recovering their inherent properties. For polymers to exhibit such a healing ability, they must contain some functionality which will either rebound among themselves or have the ability of coupling with other functionalities. Preparation of such multifunctional and well-defined macromolecules requires a smart selection of a controlled polymerization technique in combination with appropriate coupling reactions. Among all the polymerization techniques introduced so far, atom transfer radical polymerization (ATRP) is the most versatile owing to its exceptional properties like preparation of polymer with predetermined molecular weight, narrow polydispersity index, predetermined chain-end functionality, and tunable architecture. Click chemistry is an extremely powerful coupling approach which in combination with ATRP can be used for generation of polymers with almost all of the desired properties. In this chapter, an overview on the use of ATRP and click chemistry for polymerization of various “clickable” monomers using “clickable” ATRP initiators is provided along with other post-polymerization modification strategies that can be used to construct macromolecules with self-healing ability.