Atomic force microscopy study of small-size nanotubular polymer thin films
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Atomic force microscopy study of small-size nanotubular polymer thin films C. F. Zhu, I. Lee, J. W. Li, and C. Wang Institute of Chemistry, The Chinese Academy of Sciences, Beijing, 100080, People’s Republic of China
X. Y. Cao, H. Xu, and R. B. Zhang Polymer Chemistry Laboratory, Chinese Academy of Science and China Petro-chemical Corporation, Institute of Chemistry, The Chinese Academy of Sciences, Beijing, 100080, People’s Republic of China (Received 16 September 1997; accepted 1 July 1998)
In this paper, we report atomic force microscopy (AFM) images of a tubular polymer and its supermolecular polymer thin films, operated in contact mode at room temperature in air. The configuration models are also calculated using molecular dynamics. The diameter of the polymer nanotube is about 0.7 nm, the smallest size a tube can have. The results of calculation agree with the experimental results.
I. INTRODUCTION
A. Vi-T synthesized
Nanophase materials, developed since the eighties, have many different properties compared to bulk crystalline and noncrystalline materials. Many scientists studied structure and properties of nanophase materials by a number of methods.1,2 The discovery of C60 has sparked much exciting research3 related to carbon chemistry. One of the most active research fields is carbon nanotube. The C-tubes with nanometer size were synthesized by Ebbesen and Ajayan in 1992.4 An other different tubular system was synthesized by Harada et al.5–9 The tubule of SiO2 molecular sieve of nanometer scale was synthesized by self-organization processes by Tanev ˚ 10,11 and Pimravaia10 ; the diameter of the tube is 5–45 A. In general, the tubular structure was identified using x-ray,12–14 nuclear magnetic resonance (NMR),15,16 transmission electron microscopy (TEM), scanning electron microscopy (SEM),17 etc. In 1996, high resolution transmission electron microscopy (HRTEM) results on the structure character of C-nanotube were reported by Wang and Kang.18 It is known that atomic force microscope (AFM) is a powerful analysis instrument with high resolution, and it has been applied to study the surface structure of various materials successfully.19,20 In this paper, the structures of tubular polymer and its supermolecular thin films are imaged using AFM. The results are compared to that of molecular dynamics calculations. The “diameter” of the smaller tube is 0.7 nm, the smallest size a tube can have.
8.1 g (0.05 mol) of vinyltrichlorosilane and 50 ml toluene was added to a 250 ml of a three-necked flask. The flask was immerged in a mixture of water and glycerol whose temperature can be controlled in an air condition. Then the temperature of the system was reduced to 210 ±C. A solution of 5.4 g (0.05 mol) P-phylenediamine (PDA) and 50 ml of acetone was added dropwise into the flask under stirring for 3 h. 1.4 ml of water, 4.0 g of pyridine, and 15 ml of acetone were dropped into the flask under 25 ±C for 3 h. Then the reaction system was further stirred at about 25 ±C for a
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