Directional Nanoparticle Migration Driven by Mobility Gradient in Glassy Polymers

Abstract

Abstract How to precisely control the distribution of nanoparticles in a polymer matrix is a long-standing issue in polymer nanocomposites. In this work, we introduce a simple yet effective methodology to generate surface concentration gradients of nanoparticles in polymer films. The underlying mechanism relies on mobility gradients that drive the directional drift motion of nanoparticles. We first demonstrate the working principle using a poly(vinyl butyral)/iron-doped titanium dioxide (PVB/Fe-TiO2) model system, where a mobility gradient is induced by UV irradiation and visualized via fluorescence lifetime imaging microscopy. The generality of this mechanism is further validated in a PVB/silica system. This approach offers a facile and versatile route to design advanced polymer nanocomposites with tailored functional properties.