Synthesis of magnesium hydroxide nanoneedles and short nanorods on polymer dispersant template
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guang Liu College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, People’s Republic of China
Bingshe Xua) Key Laboratory of Interface Science and Engineering in Advanced Materials of Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024, People’s Republic of China; and College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, People’s Republic of China (Received 16 December 2006; accepted 8 May 2007)
Magnesium hydroxide nanoneedles and nanorods were synthesized by reverse precipitation in the presence of polyethylene glycol (MW 1000) at ambient temperature. The obtained magnesium hydroxide crystals were characterized in terms of morphology, particle size, crystal structure, and thermal stability by high-resolution transmission electron microscopy, x-ray diffraction, infrared spectroscopy, and thermogravimetric and differential thermal analysis. The experimental results show that the growth of magnesium hydroxide crystals and the dispersivity of the nanostructures were greatly influenced by polymer dispersant. The mechanism of the formation of magnesium hydroxide nanorods and nanoneedles was also proposed.
I. INTRODUCTION
In recent years, there has been growing interest in the controlled synthesis of nanostructures with special morphologies, even the ordered growth of nanostructures,1,2 because of the expectation of novel properties.1–6 However, the controlled synthesis of these materials has been a challenge due to their extremely small size, agglomeration, and difficulty in exquisite control over the shape. Magnesium hydroxide is a nontoxic, noncorrosive, antacid, thermally stable, and environmentally friendly flame retardant, undergoing endothermic dehydration and suppressing fumes under fire conditions. It is also the most important precursor for magnesium oxide with narrow size distribution, controllable structure, and morphology.7–13 It can be used as a fertilizer additive, antacid, reinforcer, and absorbent as well. Magnesium hydroxide, with special morphologies such as fiberlike, tubelike, and rodlike shapes, can be obtained by several methods, such as the hydrothermal route,7 solvothermal reaction,3,8,9 and microwave irradiation.10 All of these methods are widely used, but there are some limitations a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0315 2544 J. Mater. Res., Vol. 22, No. 9, Sep 2007 http://journals.cambridge.org Downloaded: 12 Jun 2014
to their practicability. For example, some methods suffer from the requirements of a complicated apparatus and relatively higher temperature, and others need complicated reaction processes, special conditions, or prolonged procedures. Though Lv et al.4 produced Mg(OH)2 nanoneedles and nanorods by wet precipitation, the reaction temperature must be controlled at 2 and 10 °C, respectively. As additives, high-aspect-ratio materials are beneficial to the improvement of the mechanical properties
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