Quantitative characterisation of the interactions within stimuli-responsive emulsions using FluidFM colloidal probe

Basic data for this project

Description

Stimuli-responsive Pickering emulsions combine long-term encapsulation with externally triggered release, making them highly attractive for applications in targeted drug delivery and smart catalytic systems. Despite extensive research over the past two decades, the mechanisms governing their destabilization remain poorly understood, primarily due to the challenge of probing interactions at the stabilizing particle level. A fundamental understanding of these destabilization processes is crucial for the rational design of next-generation responsive emulsions. To address this knowledge gap, we propose employing the recently developed FluidFM (fluidic force microscopy) colloidal probe method as a cutting-edge experimental tool to quantify the interactions between stabilizing soft particles and liquid interfaces. This approach will allow us to investigate interactions across multiple length scales – spanning particle, interface, and droplet levels – providing critical insights into the mechanisms driving destabilization and facilitating the rational design of more stable and reliable stimuli-responsive emulsions. This project will systematically explore three key aspects: (i) the adsorption pathways of soft core-shell microgels at liquid interfaces, (ii) the quantification of interaction forces at these interfaces under external stimuli such as temperature and pH, and (iii) the direct measurement of interactions between individual emulsion droplets under varying conditions. By integrating these findings, we aim to establish a mechanistic framework for controlling emulsion behavior with high precision. The study focuses on emulsions stabilized by temperature-responsive and pH-responsive microgel stabilizers. We will first establish FluidFM colloidal probe as a core methology in my newly formed junior research group (WP1). Simultaneously with WP1, we will synthesize core-shell microgels with an inorganic silica core and a soft poly(N-isopropylacrylamide) (PNIPAM)-based shell with varying crosslinking densities (WP2). We will use FluidFM colloidal probe to investigate their adsorption and desorption behavior at liquid interfaces (WP3). Furthermore, we analyze interactions between microgels and microgel-covered fluid interfaces (WP4). Finally, we will attach emulsion droplets to the FluidFM cantilever to quantify the interactions between microgel-covered emulsion droplets upon approach (WP5). By systematically quantifying these interactions, this study will establish a detailed force library for temperature- and pH-responsive emulsions. The results will clarify fundamental emulsion stabilization and destabilization mechanisms and support the development of more robust stimuli-responsive materials.