Theory predicts that cyanine dyes and related linear systems undergo symmetry collapse and bond localization at long chain lengths. Beyond this “cyanine limit”, the properties of these systems do not extrapolate from their shorter counterparts. To test this prediction, dipyridocyanines have been synthesized and shown to undergo such symmetry collapse with chain lengths as short as 13.

Smectic A (S A ) liquid crystalline phase developed from a new kind of mesogen-jacketed liquid crystalline polymer (MJLCP) whose mesogenic side groups are asymmetrically bonded to the main-chain was first reported. Two series of MJLCPs, poly[4,4′-bis(4-butoxyphenyloxycarbonyl)-2-vinylbiphenyl] (PBP2VBP) and poly[4,4′-bis(4-butoxyphenyloxycarbonyl)-3-vinylbiphenyl] (PBP3VBP) with different molecular weights were designed and synthesized Via atom transfer radical polymerization successfully. The chemical structures of the monomers were confirmed by elemental analysis, mass spectrometry and 1 H NMR. The molecular characterization of the polymers was performed with 1 H NMR, gel permeation chromatography, and thermogravimetric analysis. Their phase structures and transitions were investigated by differential scanning calorimetry, wide-angle X-ray diffraction and polarized light microscopy experiments. The experimental results suggest that the polymer (PBP2VBP and PBP3VBP) with asymmetry mesogenic core can develop into a well-defined smectic A (S A ) phase. This implies that the polymer molecules in the LC phase can be more ribbonlike rather than rodlike.

The nitroxide‐mediated radical polymerization of styrene was carried out on the surfaces of multiwalled carbon nanotubes (MWNTs) initiated by an MWNT‐supported initiator multiwalled carbon nanotube–2″,2″,6″,6″‐tetramethylpiperidinyloxy (MWNT–Tempo). The content of polystyrene grafted from the surface was controlled by changes in the polymerization conditions, such as the reaction times or the ratios of monomers to initiators. The obtained polystyrene‐grafted multiwalled carbon nanotubes (MWNT–PSs) were further used to initiate the polymerization of 4‐vinylpyridine to get polystyrene‐b‐poly(4‐vinylpyridine)‐grafted multiwalled carbon nanotubes (MWNT–PS‐b‐P4VPs). In contrast to unmodified MWNTs, MWNT–PSs had relatively good dispersibility in various organic solvents, such as tetrahydrofuran, CHCL3, and o‐dichlorobenzene. The structures and properties of MWNT–PSs and MWNT–PS‐b‐P4VPs were characterized and studied with several methods, including thermogravimetric analysis, Fourier transform infrared, ultraviolet–visible, and transmission electron microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4656–4667, 2006