A tetra(aniline)-based
cationic amphiphile, TANI-NHC(O)C5H10N(CH3)3+Br– (TANI-PTAB)
was synthesized, and its emeraldine base (EB) state
was found to self-assemble into nanowires in aqueous solution. The
observed self-assembly is described by an isodesmic model, as shown
by temperature-dependent UV–vis investigations. Linear dichroism
(LD) studies, combined with computational modeling using time-dependent
density functional theory (TD-DFT), suggests that TANI-PTAB molecules
are ordered in an antiparallel arrangement within nanowires, with
the long axis of TANI-PTAB arranged perpendicular to the nanowire
long axis. Addition of either S- or R- camphorsulfonic acid (CSA) to TANI-PTAB converted TANI to the emeraldine
salt (ES), which retained the ability to form nanowires. Acid doping
of TANI-PTAB had a profound effect on the nanowire morphology, as
the CSA counterions’ chirality translated into helical twisting
of the nanowires, as observed by circular dichroism (CD). Finally,
the electrical conductivity of CSA-doped helical nanowire thin films
processed from aqueous solution was 2.7 mS cm–1.
The conductivity, control over self-assembled 1D structure and water-solubility
demonstrate these materials’ promise as processable and addressable
functional materials for molecular electronics, redox-controlled materials
and sensing.
We investigated the paranematic-to-nematic phase transition of nematic main-chain liquid singlecrystal elastomers by means of high-resolution ac calorimetry and deuteron quadrupole-perturbed nuclear magnetic resonance. We determined that the cross-linking density strongly affects the thermodynamic response of the system, driving the transition from first order to supercritical via critical point of liquid-vapor type. This result together with recent findings in side-chain liquid crystal elastomers support the universality of such thermodynamic behavior in liquid crystal elastomers. Furthermore, the impact of frozen-in mechanical field during the preparation of samples has been systematically explored in this work. It is shown that the critical behavior can be controlled by both cross-linkers-induced internal random mechanical fields and frozen-in uniform mechanical field applied externally.
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