CAREER: Telechelic triblock copolymers as a platform to design functional colloidal gels

University Of Rhode Island, Kingston RI

Investigators

Abstract

Colloidal gels are a unique class of materials that behave like either solids or liquids depending on processing conditions. This flexibility makes them essential for developing the next generation of battery technology, enabling additive manufacturing processes, and mimicking the performance of biological materials. In most gels, however, the solid-like and liquid-like properties are dependent on each other, drastically limiting their utility in industrial and scientific applications. To address this critical knowledge gap, this award aims to design gels with independent elasticity and viscosity by using polymer additives. These specific polymers possess endgroups that bind to dispersed colloids to generate stiff solid-like materials that readily break down during processing to create low viscosity fluids. This approach will result in efficient and cost-effective materials comprised primarily of solvent but with mechanical properties comparable to high performance engineering materials. The properties of these polymer-linked gels will be tuned and optimized by manipulating polymer chemistry and characterized using optical microscopy and novel rheological procedures. This project will also engage in outreach efforts aimed at recruiting and retaining students in STEM fields. Outreach efforts will include hands-on experiential workshops conducted in collaboration with local community organizations, role model introductions and mentorship, and the development of a STEM-focused network for students at the University of Rhode Island. Colloidal gels are complex soft materials encountered throughout scientific and industrial applications ranging from slurries for battery production to synthetic scaffolds for tissue engineering and to inks for 3D printing. The performance of these materials depends critically on the interplay between structural and dynamical effects that underlie their emergent properties. Although many applications require competing design constraints such as robust mechanical stiffness but rapid mass transfer, the properties of most existing colloidal systems remain coupled, reducing synthetic flexibility and limiting their design. This experimental investigation of a novel class of rheological modifiers – telechelic triblock copolymers – aims to decouple the linear and nonlinear mechanical properties of colloidal gels. The chemistry of the triblock copolymers will be manipulated to generate extended conformations that promote bridge formation and drive colloidal self-assembly. Additionally, the resulting structural and dynamic heterogeneity in the polymer-linked gels will be characterized and these hierarchical properties related to nanoscale transport. Finally, the linear and nonlinear rheology of polymer-linked colloidal suspensions will be characterized using novel rheological protocols to identify high-performance yield stress fluids. These fundamental research aims will be integrated into a comprehensive educational and outreach plan that engages students in Rhode Island. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.