Bio-based nanofibers are reinforcements of increasing interest for polymer matrix composites. Nanofibers derived from cellulose and chitin are of particular interest given their abundance and anticipated mechanical properties. Beyond their individual advantages, cellulose and chitin nanofibers have opportunities to interact since they have opposite surface charges, providing another pathway for producing reinforcement. In this work, we are designing and characterizing composites containing cellulose nanocrystals (CNCs) and/or chitin nanofibers (ChNFs) and a polyvinyl alcohol (PVA) matrix with goals of understanding more fully how component interactions affect the structure-property relationships in these materials and how these interactions may be used to produce synergistic mechanical property improvements. We examined these materials in the form of composite films as well as composite hydrogels to establish any commonalities in these different composite constructs. The results of these studies indicate that three-component composites can provide improved mechanical properties with respect to the neat polymer and composites containing only CNCs or only ChNFs. Results from dynamic light scattering and rheological experiments suggest that the CNCs and ChNFs form aggregates by charge-driven association. Since the mechanical testing results show that these aggregate structures can be beneficial, we propose that the CNC/ChNF structures produced at certain CNC/ChNF ratios allow property improvement by using CNCs as a compatibilizing agent between the PVA matrix and ChNFs. Overall, these results suggest that charge-driven associations between nanofibers can lead to favorable property outcomes, providing expanded design guidelines for polymer nanocomposites.

Composites and hydrogels containing mixtures of cellulose nanocrystals and chitin nanofibers: Nanofiber assemblies and their effect on mechanical properties

ACS Spring Meeting 2021

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