Mechanically refined cellulose nanofibrils (CNFs) are promising candidates for structural applications in next generation composites, surface coatings, and biomedical materials. Due to their lower production costs, inherent renewability, and biodegradability they are well positioned to support green material development, but their surface chemistry poses unique challenges due to poor interfacial interactions with certain matrices and a propensity to lose nanoscale structure upon drying. We have developed a grafting-through approach involving a two-step, entirely aqueous based procedure to functionalize the surface of CNFs with a wide range of water soluble and insoluble polymers using traditional free radical polymerization techniques to alleviate these issues. Using FTIR characterization, atomic force, scanning electron, and optical microscopy, we have demonstrated how these modified CNFs exhibit a wide range of particle morphologies dependent on the modifications and drying methods employed. These materials are shown to retain nanoscale dimensionality under conditions in which unmodified CNFs experience significant agglomeration. The impact of these modifications on PLA composites produced via melt-mixing is explored by tensile testing, rheological characterization, and SEM analysis of fracture surfaces. This work demonstrates a versatile method for modifying the surface properties of CNFs, how these surface modifications affect particle morphology and the drying behavior of CNF suspensions, and how these factors interact to affect the reinforcing ability of these newly synthesized materials in PLA composites.

Aqueous grafting-through polymer modifications to cellulose nanofibrils: In search of a better composite

ACS Spring 2022

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