SMART CELLULOSE-BASED MATERIALS

The incorporation of small amounts of high-stiffness, high-aspect-ratio nanometer-sized fillers into polymers is a design approach that has rapidly emerged to a broadly exploited framework for the creation of new materials with tailored mechanical properties. Crystalline cellulose nanofibers are attracting significant interest in this context, mainly due to their intriguing mechanical properties and the abundance of cellulose in the biomass. These fiber-like crystals, often referred to as nanowhiskers, display an elastic modulus of 120−150 GPa and are readily obtained from renewable biosources such as bacteria, wood, cotton, and sessile sea creatures called tunicates. Owing to their strongly interacting surface hydroxyl groups, cellulose nanowhiskers have a significant tendency for self-association, which is advantageous for the formation of load-bearing percolating architectures within the host polymer matrix: the spectacular reinforcement of polymers observed for this class of materials is attributed to the formation of rigid nanowhisker networks in which stress transfer is facilitated by hydrogen-bonding between the nanowhiskers; van der Waals interactions also have been shown to play a significant role. Our experimental research program targets the design, synthesis, processing, investigation and application of a variety of bio-inspired polymer nanocomposites with stimulus-responsive mechanical properties. We have shown some of the first adaptive materials, in which a chemical stimulus causes a significant and reversible stiffness change. In addition to our ‘smart’ nano-materials based research, we are also looking into utilizing the unique properties of nanowhisker networks as reinforcing fillers for a variety of materials. Our research seeks to develop broad new design approaches. It is envisioned to adapt the new design concept to create a range of “smart” materials that respond to different stimuli in pre-programmed ways and promise to enable a plethora of technologically relevant applications.