Challenges in Synthesis and Analysis of Asymmetrically Grafted Cellulose Nanocrystals via Atom Transfer Radical Polymerization

When cellulose nanocrystals (CNCs) are isolated from microfibrils, the parallel arrangement of chains in crystalline domains is retained so that all reducing end-groups (REGs) point to one crystallite end. This permits selective chemical modification end CNCs. In this study, two reaction pathways compared selectively attach atom-transfer radical polymerization (ATRP) initiators REGs CNCs, using reductive amination. further enabled site-specific grafting anionic polyelectrolyte poly(sodium 4-styrenesulfonate) (PSS) Different analytical methods, including colorimetry and solution-state NMR analysis, were combined confirm REG-modification with ATRP-initiators PSS. The achieved yield was low due either a limited conversion CNC or side reactions on initiator during end-tethered CNCs easy redisperse water after freeze-drying, shear birefringence colloidal suspensions maintained process.