Open AccessChallenges in Synthesis and Analysis of Asymmetrically Grafted Cellulose Nanocrystals via Atom Transfer Radical Polymerization
Author(s) -
Gwendoline Delepierre,
Katja Heise,
Kiia Malinen,
Tetyana V. Koso,
Leena Pitkänen,
Emily D. Cranston,
Ilkka Kilpeläinen,
Mauri A. Kostiainen,
Eero Kontturi,
Christoph Weder,
Justin Orazio Zoppe,
Alistair W. T. King
Publication year - 2021
Publication title -
biomacromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.689
H-Index - 220
eISSN - 1526-4602
pISSN - 1525-7797
DOI - 10.1021/acs.biomac.1c00392
Subject(s) - atom transfer radical polymerization , reductive amination , cellulose , polymer chemistry , polymerization , grafting , chemistry , radical polymerization , amination , chemical engineering , materials science , organic chemistry , polymer , catalysis , engineering
When cellulose nanocrystals (CNCs) are isolated from cellulose microfibrils, the parallel arrangement of the cellulose chains in the crystalline domains is retained so that all reducing end-groups (REGs) point to one crystallite end. This permits the selective chemical modification of one end of the CNCs. In this study, two reaction pathways are compared to selectively attach atom-transfer radical polymerization (ATRP) initiators to the REGs of CNCs, using reductive amination. This modification further enabled the site-specific grafting of the anionic polyelectrolyte poly(sodium 4-styrenesulfonate) (PSS) from the CNCs. Different analytical methods, including colorimetry and solution-state NMR analysis, were combined to confirm the REG-modification with ATRP-initiators and PSS. The achieved grafting yield was low due to either a limited conversion of the CNC REGs or side reactions on the polymerization initiator during the reductive amination. The end-tethered CNCs were easy to redisperse in water after freeze-drying, and the shear birefringence of colloidal suspensions is maintained after this process.