Developing a molecular blueprint fo mechanical response

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Why is an elastic band elastic? What makes a rope stiff? How do our tendons absorb forces when we run? These questions relate to the elasticity and viscosity ("viscoelasticity") of these materials, that is, how much they deform and then return to their original shape when stress is applied and released. To design materials for specific mechanical purposes is a difficult problem, as there are many different factors to take into account. Consider the required properties of an artificial tendon: it must have a viscoelastic response similar to a native tendon, matching its stress-strain characteristics under varying conditions of load (running, walking, resting); it must exhibit these properties at and around body temperature; and it must be biocompatible, both in its long-term stability in our bodies and in its inertness (lack of toxicity) with respect to the surrounding tissues. Designing a material with specified mechanical, thermal, chemical and temporal response, and understanding this response at the molecular level are important and extremely complex problems. We propose to simplify the problem by reducing the number of molecules in the material - instead of examining tendons, we are looking at the molecules they comprise, one at a time. After characterizing the mechanical response of these building blocks, we will then combine these blocks to build more complex systems like a tendon.