Polymer brush-grafted cellulose nanocrystals for the synthesis of porous carbon-coated titania nanocomposites

Abstract

Cellulose nanocrystals (CNCs) are a renewable nanomaterials platform. Their characteristic one-dimensional morphology and surface chemistry offer opportunities for the templated synthesis of functional nanorods and nanotubes. Here we report the template-directed fabrication of mesoporous carbon-coated anatase TiO₂ nanotubes using polymer brush-grafted CNCs as nanoreactors. The nanoreactors consisted of a CNC core grafted with a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) shell made by surface-initiated atom transfer radical polymerisation (SI-ATRP). A water-soluble TiO₂ precursor, titanium(IV) bis(ammonium lactato)dihydroxide (TALH), was selectively loaded into the nanoreactor shell via ionic interactions. Pyrolysis of the CNC-g-PDMAEMA/TALH hybrids led to the carbonisation of the polymer template, the removal of the CNC core and the crystallisation of the TALH to produce carbon-coated nanocrystalline anatase. The resulting TiO₂/C nanotubes retained ∼50 wt% of TiO₂ and ∼13% wt% of carbon, and exhibited a specific surface area of ∼111 m² g⁻¹. The simultaneously forming carbon framework suppressed the growth of titania crystallites to <5 nm. We further demonstrate the potential of our TiO₂/C nanomaterials to produce titania anode materials for lithium-ion batteries.