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

Abstract

Polyimides (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 vapor-induced transformation process. First, polyamic acid (PAA) solutions are used as precursors and infiltrated into the nanochannels of anodic aluminum oxide templates, forming PAA nanotubes. After the samples are annealed in tetrahydrofuran or dimethylformamide vapors, depression of the PAA tubes occurs, causing the formation of pores. The porous PAA nanotubes can be further converted to porous PI and carbon nanotubes by imidization and carbonization processes, respectively. The pore sizes of the porous nanomaterials can be controlled by changing the type of the annealing solvent and the solvent annealing time.