Physics Colloquium: Bio-inspired pathways to manipulating architecture and mechanics in polymeric materials

Prof. LaShanda Korley, University of Delaware

Abstract: Fiber constructs are prevalent in natural systems, from collagen fiber networks in tendon to tough, spider silk fibers. Recent innovations in multilayer co-extrusion technology have translated to the fabrication of melt-extruded fiber-reinforced composites, reminiscent of the nanoscale features of the Brown Recluse Spider. Distinct advantages of this modular approach over other traditional techniques include scalability, environmentally-friendly conditions, and the ability to obtain cross- sectional dimensions on the nanoscale. Here, we describe the mechanics and structural features of biologically-relevant, reinforced hydrogels via an in situ approach. This manufacturing strategy allows for strategic control of hydrogel architecture, fiber (single component and blends) alignment and loading, compressive stability and stiffness. Promising results related to cell adherence and growth, and controlled degradation rates are highlighted for these extruded hydrogel scaffolds.

Supramolecular interactions may hold the key to the development of elastomers with a tailored elastic response and improved mechanics, such as observed in the muscle protein titin and polychaete worm jaw. It is the dynamic nature of the supramolecular interaction that we have exploited in the design of tough supramolecular elastomers that superimpose covalent and non- covalent interactions to tailor tensile response. In this research, concepts of interfacial control of self-assembly, composition, and dynamics as it relates to mechanical behavior are examined. Supramolecular blends, nanocomposites and interpenetrating networks have been investigated to achieve gradient mechanics, shape memory response, and bilayer actuation. These systems show promise in smart coating applications and for the development of functional polymer blends.