Porous Polyimide and Carbon Nanotubes: Solvent Vapor–Induced Transformation in the Nanochannels of Anodic Aluminum Oxide Templates

Abstract

nanofibrous PI membranes by electrospinning [14] ; the porous hydrophobic membranes were used for oil/water separation.Despite these works, it is still a great challenge to fabricate porous PI-based nanomaterials with controllable morphologies, properties, and sizes. In this work, we develop a novel and facile strategy to fabricate porous PI nanotubes using the template method with a solvent vapor-induced transformation process. The porous PI nanotubes are prepared by wetting the nanochannels of anodic aluminum oxide (AAO) templates with poly(pyromellitic dianhydride-co-4,4′-oxydianiline), amic acid (PAA) solutions using the solution wetting method. By introducing the solvent vapor-induced transformation process, depression of the PAA nanotubes occurs, resulting in the formation of porous PAA nanotubes. After the imidization process at 300 °C and carbonization process at 650 °C, porous PI and carbon nanotubes can be obtained, respectively. The pore lengths of the porous nanotubes can be controlled by changing the type of the annealing solvent and the solvent annealing time.In the past, polymer and carbon nanomaterials have been fabricated using different porous templates. [15][16][17][18][19][20][21][22][23] This work extends the template strategy to prepare nonporous and porous PI nanotubes. The porous PI nanotubes can also be further converted to porous carbon nanotubes, which may have potential applications in areas such as gas separation, capacitors, and energy storage devices. [24][25][26][27] Before preparing the nonporous and porous PAA, PI, and carbon nanostructures, we first examine the PAA, PI, and carbon films coated on glass substrates to confirm the viability of the imidization and carbonization processes. For the imidization process, the N−H bonds of PAA break and the N atoms connect the C atoms to form the imide rings, which can be confirmed by the disappearance of the N-H and O-H stretching bands at 2900-3200 cm −1 in the Fourier transform infrared (FTIR) spectra ( Figure S1a, Supporting Information). The CO stretching bands at 1661 cm −1 for the PAA films are also shifted and changed to symmetric stretching and asymmetric stretching vibration bands at 1777 and 1724 cm −1 , respectively, for the PI films. Moreover, the CN stretching band at 1549 cm −1 for the PAA films is shifted to 1380 cm −1 for the PI films. In addition, the CO bending band at 724 cm −1 is formed for the PI films. Porous Carbon NanotubesPolyimides (PIs) have attracted wide attention because of their exceptional thermal stability and applications in areas such as printed circuit boards and multichip modules. It remains a great challenge, however, to control the morphologies and properties of PI-based nanomaterials, especially porous PI-based nanotubes. In this work, a versatile method to fabricate porous PI nanotubes via the template method is developed, with a solvent vaporinduced transformation process. First, polyamic acid (PAA) solutions are used as precursors and infiltrated into the nanochannels of anodic aluminum oxide...

Overview of Engineering Carbon Nanomaterials Such As Carbon Nanotubes (CNTs), Carbon Nanofibers (CNFs), Graphene and Nanodiamonds and Other Carbon Allotropes inside Porous Anodic Alumina (PAA) Templates

“…However, it’s worth mentioning that the radicals and ion bombardment involved during the plasma process tend to generate a large number of defects in the crystal tube structure [ 138 , 139 ]. Consequently, the PAA templates offer an attractive approach to collectively organize CNTs in a wide range of densities and are compatible with further functionalization [ 140 , 141 ]. Then, the PAA-CNTs materials can offer a versatile platform where the control of the CNTs morphology and position can be engineered.…”

The Effect of Organic Acid Dopants on the Specific Capacitance of Electrodeposited Polypyrrole-Carbon Nanotube/Polyimide Composite Electrodes

“…Carbon-based nanomaterials such as carbon nanotubes (CNTs), carbon black, and graphene are nanofillers widely utilized in the construction of energy storage electrode materials [16][17][18][19][20][21][22]. They form electrically conductive networks throughout the entirety of the active electrode, enhancing its electrochemical performance [23].…”