Kevin Golovin1
University of Toronto1
Perfluoroalkyl Substances (PFAS) are used throughout the world in products such as greasy food packaging, outdoor apparel, wristwatch bands, cookware, and smartphone screens. However, they are carcinogenic, bio-accumulating, and cause birth defects. Given their phase-out by 2023, new sustainable polymers are needed that offer similar surface-active properties as PFAS. In this talk I will discuss my group's work developing nanoscale polydimethylsiloxane (PDMS) brushes, i.e. single chains of PDMS covalently tethered to a substrate. Unlike unfunctionalized PDMS, which exists as a liquid at room temperature (commonly known as silicone oil), or crosslinked PDMS, which is an elastomer with highly tunable mechanical properties (commonly known as silicone rubber), PDMS brushes exhibit properties of both liquids and solids. One of their myriad properties is omniphobicity, the ability to repel many different types of liquids, one of the key surface properties that PFAS were thought to uniquely exhibit. Another property is easy release or anti-fouling performance, again a characteristic typically reserved for PFAS-containing surfaces. In this talk I'll discuss how PDMS brushes may be designed to exhibit these PFAS-replacing properties and give examples of the various industries in which we've demonstrated their feasibility. Among others, these include the formulation of a PFAS-free yet oil-repellent fabric finish, grease resistant paper, ice-release coatings, and open-channel microfluidic devices. The brushes are both biodegradable and, for example, paper coated with them remains recyclable, indicating that PDMS brushes are a strong candidate for PFAS replacement.