(167r) Modulation of Interfacial Tension through Amphiphilic Block Copolymer Surfactants for Environmental Sensing

Amphiphilic block copolymers have shown great promise as modulators of interfacial tension due to their high tunability and responsivity to their surrounding environment. Specifically, they can be tuned to have dynamic and selective responses to a large variety of relevant analytes, such as pathogens and environmental toxins. Understanding the properties that govern molecular recognition and dynamic interfacial behaviors in this class of materials could potentially lead to the development of a sensor with interfacial tensions as a transduction mechanism. To this end, we investigate the effects of molecular functionalization on a model amphiphilic block copolymer, polystyrene-block-polyacrylic acid. Specifically, we measure the real-time, dynamic changes in interfacial tensions at water-oil interfaces in response to the structural transformation when exposed to various analytes using pendant drop and force tensiometry. Attachment of recognition units (i.e., chelating agents) improves selectivity toward targeted analytes (e.g., [iron, lead, and cadmium]). We use Fourier Transform Infrared (FTIR) Spectroscopy to confirm functionalization, and metal complexation is confirmed with UV-Vis Spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Furthermore, we demonstrate the change in polymer configuration upon complexation with Dynamic Light Scattering (DLS). Lastly, we incorporate this functionalized block copolymer into complex double emulsions for in situ measurements. Overall, this block copolymer-based methodology provides the framework for rapid and on-site sensing of mining byproducts (e.g., waste metals) that continue pollute the water supply of the American Southwest.