TY - JOUR
T1 - On the polymorphic and morphological changes of cellulose nanocrystals (CNC-I) upon mercerization and conversion to CNC-II
AU - Jin, Ersuo
AU - Guo, Jiaqi
AU - Yang, Fang
AU - Zhu, Yangyang
AU - Song, Junlong
AU - Jin, Yongcan
AU - Rojas, Orlando J.
PY - 2016/6/5
Y1 - 2016/6/5
N2 - Polymorphic and morphological transformations of cellulosic materials are strongly associated to their properties and applications, especially in the case of emerging nanocelluloses. Related changes that take place upon treatment of cellulose nanocrystals (CNC) in alkaline conditions are studied here by XRD, TEM, AFM, and other techniques. The results indicate polymorphic transformation of CNC proceeds gradually in a certain range of alkali concentrations, i.e. from about 8% to 12.5% NaOH. In such transition alkali concentration, cellulose I and II allomorphs coexists. Such value and range of the transition concentration is strongly interdependent with the crystallite size of CNCs. In addition, it is distinctively lower than that for macroscopic fibers (12-15% NaOH). Transmission electron microscopy and particle sizing reveals that after mercerization CNCs tend to associate. Furthermore, TEMPO-oxidized mercerized CNC reveals the morphology of individual nanocrystal of the cellulose II type, which is composed of some interconnected granular structures. Overall, this work reveals how the polymorphism and morphology of individual CNC change in alkali conditions and sheds light onto the polymorphic transition from cellulose I to II.
AB - Polymorphic and morphological transformations of cellulosic materials are strongly associated to their properties and applications, especially in the case of emerging nanocelluloses. Related changes that take place upon treatment of cellulose nanocrystals (CNC) in alkaline conditions are studied here by XRD, TEM, AFM, and other techniques. The results indicate polymorphic transformation of CNC proceeds gradually in a certain range of alkali concentrations, i.e. from about 8% to 12.5% NaOH. In such transition alkali concentration, cellulose I and II allomorphs coexists. Such value and range of the transition concentration is strongly interdependent with the crystallite size of CNCs. In addition, it is distinctively lower than that for macroscopic fibers (12-15% NaOH). Transmission electron microscopy and particle sizing reveals that after mercerization CNCs tend to associate. Furthermore, TEMPO-oxidized mercerized CNC reveals the morphology of individual nanocrystal of the cellulose II type, which is composed of some interconnected granular structures. Overall, this work reveals how the polymorphism and morphology of individual CNC change in alkali conditions and sheds light onto the polymorphic transition from cellulose I to II.
KW - Cellulose I and II
KW - Cellulose nanocrystals
KW - CNC
KW - Crystallinity
KW - Crystallite size
KW - Mercerization
KW - Polymorphs
UR - http://www.scopus.com/inward/record.url?scp=84959482761&partnerID=8YFLogxK
U2 - 10.1016/j.carbpol.2016.01.048
DO - 10.1016/j.carbpol.2016.01.048
M3 - Article
AN - SCOPUS:84959482761
SN - 0144-8617
VL - 143
SP - 327
EP - 335
JO - Carbohydrate Polymers
JF - Carbohydrate Polymers
ER -