Self-Assembled Template Assisted Gram-Scale Synthesis of Uniform Silica Nanotubes for Proton Conductivity Enhancement

Abstract

Marine organisms such as diatoms and sponges fabricate hierarchically ordered siliceous architectures with nanoscale precision under benign conditions. Inspired by these biological strategies, biomimetic approaches have been developed to synthesize chiral silica-based materials under mild conditions. Here, we employed the molecular self-assembly of a small molecule viz. l-NapF-EDA to template the formation of chiral, anisotropic silica nanotubular structures. The self-assembly of l-NapF-EDA spontaneously generates a localized basic microenvironment near the nanofiber surface, directing silica condensation and enabling the controlled formation of uniform silica nanotubes without the need for an external base. The resulting nanotubes exhibit a well-defined hollow tubular morphology with an outer diameter of 61.26 ± 12.5 nm and an inner diameter of 39.6 ± 4.3 nm, yielding a high aspect ratio characteristic of one-dimensional (1D) nanostructures. Notably, the self-assembly templated mineralization process affords a remarkably high product yield: 1.5 g of silica nanotubes can be produced from as little as 100 mg of gelator, underscoring the efficient templating capability of the supramolecular scaffold. Postsynthetic amine functionalization imparts tunable surface chemistry while preserving the nanotubular morphology. Leveraging the elongated architecture and interfacial functionality of these silica nanotubes, they were incorporated into sulfonated poly(vinyl alcohol) (SPVA) membranes, achieving 45% enhancement in proton conductivity at room temperature (61.1 ± 1.2 vs 42.1 ± 1.6 mS cm^–1) with an ultralow filler loading of 0.1 wt % relative to pristine SPVA. These results demonstrate how biomimetic mineralization and interfacial engineering can be integrated to develop functional materials with tailored properties.