Matrix-engineered electrospun MIP–MWCNT nanofiber interfaces for programmable ammonia recognition and transduction

Abstract

Electrospun polymer nanocomposites offer a versatile route to engineer functional interfaces in which molecular recognition, analyte transport, hydration and electrical transduction are integrated within a single fibrous layer. However, the host polymer is often treated mainly as a processable carrier, although its chemistry and morphology can strongly regulate the final material response. Here, we demonstrate matrix-engineered electrospun MIP/MWCNT nanofiber interfaces as programmable ammonia-responsive materials, where ammonium-templated molecularly imprinted polymer nanoparticles provide template-derived recognition domains and the polymer matrix controls analyte accessibility, hydration-mediated transport and conductive-network modulation. A fixed NH 4 + -MIP nanoparticle formulation and MWCNT loading were incorporated into electrospun poly(vinylpyrrolidone) (PVP), polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) matrices to systematically probe the contribution of the host-polymer environment while maintaining the MIP formulation and relative MIP/MWCNT loadings fixed. This matrix selection was conceived as a deliberate materials-design strategy to create distinct polymer-controlled microenvironments for tuning ammonia accessibility, hydration-mediated transport and electrical transduction under complex and humidity-variable operating conditions. Although based on the same recognition and transduction components, the three interfaces exhibited distinct nanofibrous architectures, humidity-dependent baseline resistances and NH 3 response profiles. Sensitivities varied by more than one order of magnitude, from 0.006 to 0.08 ppmv −1 for PMMA to 0.03–0.09 ppmv −1 for PAN and 0.3–0.35 ppmv −1 for PVP. PVP favoured rapid, high-amplitude responses with early saturation, PAN enabled a broader quasi-linear operating range, and PMMA displayed weaker amplification and slower recovery. Rather than identifying a single optimal polymer carrier, the comparison defines distinct matrix-dependent operating regimes in which sensitivity, usable response range, humidity dependence, and response/recovery kinetics are differently balanced within the same MIP/MWCNT sensing architecture. The comparison reveals that ammonia response is governed not only by the presence of imprinted recognition sites, as supported by the lower response of non-imprinted controls, but also by matrix-controlled fiber morphology, aggregate organization, humidity response and MWCNT percolation. These findings establish the host polymer as an active design variable for programming and tuning recognition-transport-transduction coupling in electrospun MIP/CNT interfaces. This approach shifts MIP-based chemiresistive design beyond simple recognition-site incorporation toward matrix-programmed functional interfaces, providing a materials-guided framework for tailoring ammonia-responsive behavior through polymer chemistry, hydration, fiber architecture, and conductive-network organization.