Drawing inspiration from the sea cucumber dermis as a biomodel, researchers at CWRU have recently introduced the concept of stimuli-responsive nanocomposites where the mechanical properties of the materials are altered by controlling the interactions between the rigid filler components. Using cellulose nanocrystals (CNCs), which contain hydroxyl groups on their surface, as the rigid filler in a polymer matrix high modulus nanocomposite films are obtained when the films are dry and strong interactions can occur between the filler components. However, upon exposure to water, which disrupts the filler-filler interactions, a dramatic reduction in modulus is observed in these films. This proposal is focused on exploration of the fundamentals of this nanocomposite switching mechanism with the goal of obtaining a better understanding of how different chemistries of the CNC surface can impact the switching capability of the nanocomposites and the reinforcement characteristics in different polymer matrices. Building on this fundamental knowledge and using chemistry from the literature developed in the CWRU group, a series of CNCs that contain carboxylate, amine, polymeric or metal binding units on their surface will be prepared and studied both as dispersions and in their nanocomposite form. In addition, with the aim of developing a better understanding of how the different CNC surface chemistries impact the properties of these nanocomposites, a key goal of this project is to expand and develop this new class of mechanically-adaptable materials. The PI's group will study nanocomposites that respond in different ways (e.g. stiff to soft or soft to stiff) to different stimuli (i.e, pH, metal ion, temperature or mechanical impact) as well as materials that are also multi-responsive (i.e. show different responses to different stimuli).
NON-TECHNICAL SUMMARY:
Researchers at CWRU are using the sea cucumber dermis as bioinspiration to develop a new class of stimuli-responsive or adaptive materials. The materials are nanocomposites comprised of a cellulose nanofiber scaffold embedded with a polymer matrix. This reinforcing scaffold can be disassembled by switching off the interactions between the biorenewable cellulose nanofibers which results in a dramatic softening of the material. The proposed research will yield blueprints for a class of advanced, mechanically-adaptive materials with a substantial application potential ranging from new materials for cortical implants to adaptive protective clothing, and active vibration dampening systems. The research is complemented with educational elements that amalgamate research and education and provide stimulating experiences at both the undergraduate and graduate levels, implementing outreach to high school and elementary school students as well as directly with the general public.
