title: On the polymorphic and morphological changes of cellulose nanocrystals (CNC-I) upon mercerization and conversion to CNC-II.
abstract: 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.
authors.affiliation: Jiangsu Provincial Key Lab. of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, Jiangsu, Peoples Republic of China.
authors.forename: Ersuo
authors.initials: E
authors.lastname: Jin
authors.affiliation: Bio-based Colloids and Materials, School of Chemical Technology, Aalto University, PO Box 16300, Aalto FIN-00076 Espoo, Finland.
authors.forename: Jiaqi
authors.initials: J
authors.lastname: Guo
authors.affiliation: Jiangsu Provincial Key Lab. of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, Jiangsu, Peoples Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Jiangsu Provincial Key Lab. of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, Jiangsu, Peoples Republic of China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Jiangsu Provincial Key Lab. of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, Jiangsu, Peoples Republic of China; Bio-based Colloids and Materials, School of Chemical Technology, Aalto University, PO Box 16300, Aalto FIN-00076 Espoo, Finland. Electronic address: junlong.song@njfu.edu.cn.
authors.forename: Junlong
authors.initials: J
authors.lastname: Song
authors.affiliation: Jiangsu Provincial Key Lab. of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, Jiangsu, Peoples Republic of China.
authors.forename: Yongcan
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Bio-based Colloids and Materials, School of Chemical Technology, Aalto University, PO Box 16300, Aalto FIN-00076 Espoo, Finland. Electronic address: orlando.rojas@aalto.fi.
authors.forename: Orlando J
authors.initials: OJ
authors.lastname: Rojas
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D053758:Nanoparticles; D010084:Oxidation-Reduction; D010316:Particle Size; D010880:Piperidines / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: C528764:2,2,6,6-tetramethyl-1-piperidine; D010880:Piperidines; D012972:Sodium Hydroxide; D002482:Cellulose
keywords: CNC; Cellulose I and II; Cellulose nanocrystals; Crystallinity; Crystallite size; Mercerization; Polymorphs