Natural materials, such as silk and cellulose, have an inspiring set of properties, which have evolved over hundreds of millions of years. Taking inspiration from these materials, novel functionalized materials mimicking aquamelts are constructed by combining cellulose nanocrystals (CNC) and regenerated silk fibroin (RSF) from <i>Bombyx mori</i>. An aquamelt is a water-polymer complex that can transition from a soluble liquid state to an insoluble fiber through a stress input. CNCs are negatively charged colloidal particles with high crystallinity and they were surface modified via amination to enhance the attractive interactions with silk. CNCs are expected to bring order and alignment along with reinforcing ability whereas RSF provides soft and more mobile regions to further facilitate the alignment of the final fiber structure. Interactions and compatibility between CNCs and silk were studied using a quartz crystal microbalance with dissipation monitoring (QCM-D). The aim was to determine whether ionic interactions between CNC and RSF are enough for sufficient binding or whether covalent crosslinking is needed. RSF was successfully adsorbed on CNCs with different surface charges; however, ionic interactions were not strong enough to hold all the adsorbed RSF on the surface. For this reason, covalent crosslinking of the two components is needed, which was achieved by bioconjugation, and again the interactions between the components was determined by QCM-D. Rheological properties of the different CNC-RSF mixtures was studied to determine their suitability for fiber spinning. Under shear, due to the rod-like morphology, CNCs naturally align along the shear direction, exhibiting three distinct regions, which is a typical rheological behavior for a lyotropic liquid crystal polymer. RSF as such does not possess this type of property and does not show orientation. Due to the verified interactions between CNC and RSF it was hypothesized that CNC would induce alignment of silk under shear. The steady shear rheology measurements and simultaneous polarized light imaging showed orientation of some of the mixtures in flow. This was confirmed by the appearance of the Maltese cross due to birefringence. Ionic interactions were observed to be more favorable for inducing alignment of silk than covalent crosslinking. In conclusion, the CNCs are able to induce alignment of RSF, and could lead to materials that can be spun into fibers with good mechanical properties.

Combining properties of ordered cellulose nanocrystals and mobile silk proteins to facilitate orientation in flow

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.