Description:

A common hallmark amongst biological interfaces are hierarchical surface features. These topographical structures vary in type and quality (e.g., wrinkles, folds, pillars), and often impact key interfacial properties including wettability, adhesive character, and even provide surfaces with structural color. This talk will address ongoing efforts in Dr. Szczepanski’s group to examine the formation of surface instabilities and hierarchical structures in polymer materials. The first project presented investigates how heterogeneous and phase-separating polymerizations can be leveraged to create hierarchical structures in photopolymerized, glassy coatings. Specifically, when phase domains with large differentials in modulus form during polymerization, unique surface topographies on the micro- and macroscale form. These features are qualitatively different than expected classical wrinkling instabilities observed in soft materials. Furthermore, the quality of surface patterning can be manipulated through reaction engineering. This presents a unique opportunity in interface design, as multiple end products are accessible from a single polymerization system. The second portion of the talk will present our ongoing investigations into transient instabilities, such as creasing and wrinkles, that arise during swelling of un-constrained polymer gels. We identify material parameters that influence the size and half-life of instabilities during swelling, and provide forward perspective as to how instability regimes in soft materials can inform the design of smart and active soft matter systems.

Caroline Szczepanski, Assistant Professor, Chemical Engineering and Materials Science,  Michigan State University

Host: Michelle Driscoll