Fabrication of polyimide nanotubes and carbon nanotubes containing magnetic iron oxide in confinement

Abstract

Polyimide nanotubes with tunable wall thickness were fabricated by a precursor impregnation method using an AAO template, and carbon nanotubes containing magnetic iron oxide were obtained using ferric chloride-embedded polyimide precursor by a carbonization process. Nanotubular materials have attracted considerable attention owing to their various applications in the fields of electronics, optics, catalysis, energy storages, and bio-sensors.1 Up to date, diverse methods for the preparation of inorganic and organic nanotubes such as titania, silica, and pyrene have been developed. 2Polymer nanotubes could also be prepared by several synthetic methods including a soft or hard template-assisted approach, selfassembly, sol-gel methods, and electospinning. 3 Most research has focused on thermoplastics and conducting polymer. On the other hand, there is limited information concerning the fabrication of thermoset nanomaterials using mesoporous silica and block copolymer as a template. 4 Hillmyer et al. and Mijovic groups have reported the synthesis of thermoset nanostructured materials from self-assembled amphiphilic block copolymer/epoxy resin mixture. Among thermoset polymers, aromatic polyimides are important materials because they have excellent mechanical, dielectric and thermal properties. 5 Recently, electrospinning and drying-jet techniques have been used for the fabrication of polyimide hollow fibers. 6 However, polyimide nanotubes have not been synthesized yet and this is the first demonstration of a fabricated polyimide tubular structure using a precursor impregnated AAO template method. The hard template method provides not only facile synthesis of the desired material within the cylindrical and spherical porous substrates but also the ability to control the wall thickness of tubular materials. Precise control of the wall thickness can enhance physical and chemical properties such as electrical conductivity, surface area, permeability, and selectivity of the nanotubes. These improved performances could be applied in various research fields, e.g. in chemical and biological sensors, catalysts, separation system, double layer capacitors and hydrogen storage systems. 7Carbon nanotubes have been studied for their extensive application fields as well as the fabrication methods. The polymer precursor-mediated method has excellent advantages in the fabrication of tailored carbon nanotubes and for introducing foreign materials that exhibit functional properties such as magnetic, photonic, and biological properties into the carbon nanotube. 8 In particular, magnetic carbon nanotubes have been used for magnetic data storage, improved magnetic tapes, and heterogeneous catalysis. 9 The fabrication of carbon nanotubes with magnetic properties and tunable wall thickness is therefore a challenge. Herein we report on the facile synthesis of polyimide nanotubes using an AAO template and the conversion into carbon nanotubes through the carbonization process. Scheme 1 illustrates the overall synthetic procedure of fabrication ...

Versatile strategies for fabricating polymer nanomaterials with controlled size and morphology

“…Interestingly, thermosetting polyimide nanofibers with tailored wall-thicknesses could be also fabricated by wetting the polymer precursor solution in the channels of the alumina membrane, followed by a curing process. 174 On the other hand, conducting polymer nanotubes have been extensively synthesized by chemical 175,176 and electrochemical 177-179 polymerization using porous membranes. Polyelectrolytes could be deposited within the cylindrical pores of templates to obtain nanotubes.…”

Decoration of carbon nanotubes with iron oxide

“…The studies are focused on the process of impregnating CNTs with iron oxide [1,12], the electric and magnetic properties of the composite [13,14], catalysis using of magnetic carbon nanomaterials [15,16], and so on. For CNTs impregnated with iron oxide, Jang et al [12] reported a process to fabricate g-Fe 2 O 3 -impregrated magnetic CNTs using polymer nanotubes as the carbon precursor.…”

“…The studies are focused on the process of impregnating CNTs with iron oxide [1,12], the electric and magnetic properties of the composite [13,14], catalysis using of magnetic carbon nanomaterials [15,16], and so on. For CNTs impregnated with iron oxide, Jang et al [12] reported a process to fabricate g-Fe 2 O 3 -impregrated magnetic CNTs using polymer nanotubes as the carbon precursor. For the electric and magnetic properties of the composite, Jiang et al [13] prepared MWNTs-magnetite nanocomposites by in situ solvothermal method and discussed the electric properties of them; Correa-Duarte et al [14] achieved the magnetic functionalization of CNTs by coating with iron oxide nanoparticles through the polymer wrapping and layer-bylayer assembly techniques, and aligned magnetic CNTs under low magnetic fields.…”

Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal

“…The anodic aluminum oxide (AAO) membrane has been widely used as a template for the fabrication of carbon, metal and polymer nanofibers or nanotubes due to its well-defined nano-size channels [14][15][16][17]. Recently, several studies have been reported that the AAO membrane could be used as a membrane itself (without etching process) [18,19].…”