Tailoring Nanopore Geometry in Anodic Aluminum Oxide Membranes through Physical Stretching and Controlled Anodization

The fabrication and application of anodic aluminum oxide (AAO) membranes with tailored nanopore geometries have profound implications in materials science and engineering. This study introduces a refined physical stretching method combined with precisely controlled anodization conditions to manipulate the anisotropy of nanopores in AAO membranes. By employing high-purity aluminum sheets and varying electrolytes such as sulfuric acid, oxalic acid, and phosphoric acid, anisotropic shapes are carried out with aspect ratios varying based on the applied mechanical forces and electrolytic conditions. The capability to produce AAO membranes with non-uniform pore distributions is also demonstrated by applying irregular stretching forces, revealing the potential for creating customized nanostructures. The anisotropic AAO membranes serve as effective templates for synthesizing polymer nanorods, indicating their utility in guiding the formation of advanced nanomaterials with specific directional properties. Our results showcase the role of mechanical and chemical parameters in tailoring nanoscale material properties. The versatility of horizontally anisotropic AAO membranes in nanofabrication enables better control of nanopore geometry for applications in nanoelectronics, drug delivery, and biosensing.