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First Preparations and Characterization of Conductive Polymer Crystalline Nanoneedles
Author(s) -
Su Kai,
Nuraje Nurxat,
Zhang Lingzhi,
Chu IWei,
Matsui Hiroshi,
Yang NanLoh
Publication year - 2009
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200950501
Subject(s) - materials science , conductive polymer , polyaniline , polythiophene , polymer , nanotechnology , high resolution transmission electron microscopy , polymerization , polypyrrole , conductive atomic force microscopy , crystal (programming language) , chemical engineering , crystallization , organic electronics , transmission electron microscopy , composite material , physics , transistor , quantum mechanics , atomic force microscopy , voltage , computer science , engineering , programming language
Single crystalline nanoneedles of three families of the most studied conductive organic polymers ‐ polythiophene, polyaniline and polypyrrole ‐ were synthesized for the first time using an interfacial polymerization process that takes place with simultaneous crystallization. As the crystal growth is concurrent with polymerization, more ordered crystal packing can be expected. Most of the bulk conducting‐polymer systems studied contains regions that are inhomogeneous. Single nanocrystals of conducting polymers have not been reported, although needle‐shaped bulk crystals of the quarterphenyl cation radical salt have previously been studied. The investigation of processes in a nanodomain of a single crystal is critical in ascertaining the inherent electronic properties of polymer nanoelements. The organic conductive nanoneedles were characterized using TEM, HRTEM, electron diffraction, EDS, and EPR to establish their crystal structure and composition. Scanning tunneling microscopy/spectroscopy (STM/STS) investigation were conducted to examine their electronic behaviors, leading to the discovery of a field‐induced conductance switching with response times on the millisecond level. The switch voltages are in the range of 3 to 4 volts in STM experiments, consistent with the trend of the band gap of the three polymers. The organic conductive nanoneedles with nano‐tip having high density of mobile electron may serve as interesting elements for nanoscale electronics.