Aqueous-Based Polyimine Functionalization of Cellulose Nanofibrils for Effective Drying and Polymer Composite Reinforcement

A simple strategy was developed to synthesize polyimine-coated cellulose nanofibrils (CNF) for effective CNF drying and composite reinforcement. The polyimine was synthesized in an aqueous medium using a selective hydrophilic and hydrophobic component that forces the polyimine to precipitate, which prevents the reverse imine reaction. The polyimine coating allowed the CNF to be easily oven-dried while maintaining a fibrillar morphology to provide mechanical reinforce-ment in poly(ethylene terephthalate glycol) (PETG) composites. In comparison, poor mechanical performance and a heterogeneous fracture surface were observed when the coated CNF were incorporated into poly(L-lactide) (PLA) composites. It is hypothesized that intermolecular aromatic-aromatic interactions are formed at the interface between fibers and the polymer matrix in the PETG system, while no such phenomena occur in the PLA system. Overall, this facile strategy to produce modified, easily dried CNF can be adapted to produce polyimine-coated CNF with unique functionalities that are useful in a range of applications.

Automated summary

A simple strategy of synthesizing polyimine-coated cellulose nanofibrils (CNF) was developed for composite reinforcement. The polyimine coating allows CNF to be easily dried while maintaining its morphology and providing mechanical reinforcement in certain polymer composites. However, the coating may not be effective in other composite systems.