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The telechelic polystyrene (tPS) was used as a macro-reversible addition fragmentation chain transfer (RAFT) agent to prepare the ABA-type tri-block copolymers (TBCs), poly{4-[4-(11-acryloyloxyundecyloxy)phenylazo]benzonitrile}-b-polystyrene-b-poly{4-[4-(11-acryloyloxyundecyloxy)phenylazo]benzonitrile} [poly(AUPAB)-b-PS-b-poly(AUPAB)] with 4-[4-(11-acryloyloxyundecyloxy)phenylazo]benzonitrile (AUPAB) as a monomer by the RAFT polymerization process. The poly(AUPAB) was used as a reference to probe the role of polystyrene block in poly(AUPAB)-b-PS-b-poly(AUPAB) macromolecular chain. The TBCs were characterized by spectral techniques, thermal analysis, and polarizing optical microscopic studies and compared the results with individual blocks, poly(AUPAB), and tPS. The TBCs exhibited higher thermal stability and liquid crystal–isotropic phase transition peak temperature (TLC-I), and glass transition temperature (Tg) values compared to the poly(AUPAB). TBCTLC-Ivalue was dependent on the AUPAB wt% in macromolecular chain. Furthermore, the acquired results by optical microscopy suggest that after incorporation of the polystyrene block in acrylate-based pendant azobenzene polymer chain resulted in lower domain size of focal conic texture, which is characteristic of smectic-A liquid crystalline phase compared to the homopolymer. The photophysical properties of the TBCs were similar to those of the poly(AUPAB). Microphase-separated nano-segregation was observed in annealed thin films of TBCs. [ABSTRACT FROM AUTHOR]

We report studies on the rheological properties of a liquid crystalline analog of Abrikosov phase in type-II superconductors known as twist-grain-boundary-A (TGBA) phase. The TGB.t phase shows a large apparent yield stress compared to the cholesteric (N*) phase. The storage modulus (G') of the TGBA phase is significantly larger than the loss modulus (G "). The dynamic relaxation measurements indicate a solid-like behavior of N*, TGBA, and smectic-C* phases. The complex shear modulus of the TGBA, phase exhibits a power-law behavior G*(ω) ~ ωαof with a ⋍0.5. The relative amplitude of G' and G" at various temperatures indicate that the enhanced elasticity of TGBA phase is due to the structural defects. [ABSTRACT FROM AUTHOR]

Carbon Nanotubes (CNT) were discovered by Ijjima (1991). Since then, they have caused considerable excitement among researchers due to their potential technological applications. It is believed that Carbon Nanotube Field Effect Transistor (CNTFET) will be one of the most promising electronic devices to replace silicon Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) in the near future. If that be so, then we need to know the electrical properties of CNT. In this paper we have reviewed and given an insight into the electronic structure of carbon nanotubes and also discussed how chirality plays a vital role in determining such properties. Electronic Density of States (DOS) and phonon dispersion of CNT which are central to understanding the electronic properties, are also discussed for different CNTs. We have also discussed about CNTFET, its classification and finally a comparison between CNTFET and MOSFET is given. [ABSTRACT FROM AUTHOR]