Co-Dosing Vapor Phase Infiltration within Epoxidized Isoprene for Functional Al-Doped ZnO and AlO_<i>x</i>–ZnO Composites

Compositional control is crucial in achieving the desired material properties across various applications, such as catalysis, energy storage, and semiconductor devices. Vapor phase infiltration (VPI) enables the direct transformation of polymeric nanostructures into inorganic nanostructures. However, conventional VPI processes typically utilize a single organometallic precursor, limiting the material synthesis to singular compositions. Here, we demonstrate a co-dosing VPI approach that overcomes this limitation by precisely controlling the partial pressures of the precursors, significantly expanding VPI capabilities for synthesizing composite and doped materials. Using trimethylaluminum (TMA) and diethylzinc (DEZ) precursors with an epoxidized isoprene (EPI) homopolymer and polystyrene-block-poly(epoxyisoprene) (PS-b-EPI) block copolymer films, we successfully fabricated Al-doped ZnO and AlOx-ZnO composite materials with controllable aluminum (Al) incorporation ranging from 1.6 to 28%. Employing scanning transmission electron microscopy energy-dispersive X-ray spectroscopy cross-sectional analysis before and after thermal treatment, we identify characteristic infiltration and growth mechanisms of TMA versus DEZ, and we reveal differential growth behaviors between the homopolymer and block copolymer. The co-dosing approach demonstrated herein substantially broadens VPI applications, providing a versatile pathway for fabricating precisely tailored composites and doped nanostructures.