Morphological Evolution of Self-Assembled Polyaniline Nanostuctures Obtained by pH-stat Chemical Oxidation

被引:102
作者
Laslau, Cosmin [1 ]
Zujovic, Zoran D. [1 ]
Zhang, Lijuan [1 ]
Bowmaker, Graham A. [1 ]
Travas-Sejdic, Jadranka [1 ,2 ]
机构
[1] Univ Auckland, Dept Chem, Polymer Elect Res Ctr, Auckland, New Zealand
[2] MacDiarmid Inst Adv Mat & Nanotechnol, Wellington, New Zealand
关键词
DOPED POLYANILINE; DISPERSION POLYMERIZATION; ELECTRICAL-CONDUCTIVITY; FORMATION MECHANISM; NANOTUBES; ANILINE; NANOSTRUCTURES; TEMPLATE; NANORODS; MICRO/NANOSTRUCTURES;
D O I
10.1021/cm803447a
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The chemical oxidation of polyaniline is carried out at constant acidity, investigating six separate pH levels (pH = 1, 2, 3, 4, 5, and 6). All prior studies on polyaniline self-assembly used a falling-pH or a temporarily buffered falling-pH method, making this the first application of pH-stat techniques to the study of polymer nanostructure formation. This allows us to isolate with improved precision the various nanostructures formed at different stages of polyaniline self-assembly, which include spheres, flakes and ribbons at neutral pH, fibers and tubes at mildly acidic pH, and grains at highly acidic pH. The evolution of these structures is investigated as a function of both pH and time. This approach results in the observation of two previously unnoticed phenomena: the morphology is found to evolve as a function of time even when pH is kept constant, and polyaniline nanotubes are formed at a constant acidity. Both of these results have important implications for existing self-assembly theories. Fourier transform infrared spectroscopy is used to investigate the polyaniline compositional and structural evolution underlying the visible morphological changes and shows that as pH falls there is increased protonation, decreased orthocoupling, lower phenazine presence, and less sulfonation. The time evolution, on the other hand, shows increased sulfonation and decreased oxidation. Ultraviolet-visible spectroscopy shows a mixture of delocalized and localized polaron behavior for the pH-1-stat to pH-3-stat products, and insulating characteristics for the higher pH structures. This is confirmed by four-point conductivity measurements.
引用
收藏
页码:954 / 962
页数:9
相关论文
共 79 条
[61]   Studies on multi morphology of polyaniline guided by alkali [J].
Wang, X. ;
Liu, N. ;
Zhang, W. J. .
NANOSCIENCE AND TECHNOLOGY, PTS 1 AND 2, 2007, 121-123 :429-432
[62]   Synthesis and physical properties of highly sulfonated polyaniline [J].
Wei, XL ;
Wang, YZ ;
Long, SM ;
Bobeczko, C ;
Epstein, AJ .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1996, 118 (11) :2545-2555
[63]  
Wei ZX, 2002, LANGMUIR, V18, P917, DOI [10.1021/la0155799, 10.1021/l0155799]
[64]   Nanobeam mechanics: Elasticity, strength, and toughness of nanorods and nanotubes [J].
Wong, EW ;
Sheehan, PE ;
Lieber, CM .
SCIENCE, 1997, 277 (5334) :1971-1975
[65]   CAMPHORSULFONIC ACID FULLY DOPED POLYANILINE EMERALDINE SALT - CONFORMATIONS IN DIFFERENT SOLVENTS STUDIED BY AN ULTRAVIOLET-VISIBLE NEAR-INFRARED SPECTROSCOPIC METHOD [J].
XIA, YN ;
WIESINGER, JM ;
MACDIARMID, AG ;
EPSTEIN, AJ .
CHEMISTRY OF MATERIALS, 1995, 7 (03) :443-445
[66]   Optical and mechanical properties of vacuum evaporated vapour chopped polyaniline thin film [J].
Yadav, J. B. ;
Puri, R. K. ;
Puri, V. .
APPLIED SURFACE SCIENCE, 2007, 253 (20) :8474-8477
[67]   Preparation of nanostructured polyaniline and its super-amphiphilic behavior [J].
Zhang, Haibin ;
Wang, Jixiao ;
Zhou, Zhibin ;
Wang, Zhi ;
Zhang, Fengbao ;
Wang, Shichang .
MACROMOLECULAR RAPID COMMUNICATIONS, 2008, 29 (01) :68-73
[68]   Structural Characteristics of Polyaniline Nanotubes Synthesized from Different Buffer Solutions [J].
Zhang, Lijuan ;
Zujovic, Zoran A. ;
Peng, Hui ;
Bowmaker, Graham A. ;
Kilmartin, Paul A. ;
Travas-Sejdic, Jadranka .
MACROMOLECULES, 2008, 41 (22) :8877-8884
[69]   Characterization of polyaniline nanotubes formed in the presence of amino acids [J].
Zhang, Lijuan ;
Peng, Hui ;
Zujovic, Zoran D. ;
Kilmartin, Paul A. ;
Travas-Sejdic, Jadranka .
MACROMOLECULAR CHEMISTRY AND PHYSICS, 2007, 208 (11) :1210-1217
[70]   Molybdic acid doped polyaniline micro/nanostructures via a self-assembly process [J].
Zhang, Lixia ;
Zhang, Lijiuan ;
Wan, Mexiang .
EUROPEAN POLYMER JOURNAL, 2008, 44 (07) :2040-2045