A comparative study on the preparation and characterization of cellulose nanocrystals with various polymorphs

Jie Gong; Lihuan Mo; Jun Li

doi:10.1016/j.carbpol.2018.04.039

A comparative study on the preparation and characterization of cellulose nanocrystals with various polymorphs

Carbohydr Polym. 2018 Sep 1:195:18-28. doi: 10.1016/j.carbpol.2018.04.039. Epub 2018 Apr 12.

Authors

Jie Gong¹, Lihuan Mo¹, Jun Li²

Affiliations

¹ State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; United Lab of Plant Resources Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
² State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; United Lab of Plant Resources Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China. Electronic address: ppjunli@scut.edu.cn.

PMID: 29804966
DOI: 10.1016/j.carbpol.2018.04.039

Abstract

Polymorphic changes of cellulose nanocrystals (CNCs) are strongly associated with its properties and applications. In this study, CNCs with different polymorphs were produced by a simple polymorphic transformation treatment. Cellulose I nanocrystals were produced by typical sulfuric acid hydrolysis (CNC-I). Cellulose II nanocrystals were prepared by two different methods: (1) sulfuric acid hydrolysis of cellulose previously mercerized with 18.5 wt% NaOH (CNC-II), (2) mercerization of CNC-I with 18.5 wt% NaOH (MCNC-II). Cellulose III nanocrystals were prepared by ethylenediamine treatment of CNC-I (ECNC-III). The polymorphic changes of CNCs, and their properties including morphology, crystallinity, thermal stability, and re-dispersion ability were systematically investigated. The results showed that the other properties of CNC-II and MCNC-II were quite different from each other except for the morphology. The morphology of polymorphic transformed CNCs were strongly relate to the fashion of cellulose chains arrangement. Both CNC-II and MCNC-II exhibited a rod-like shape with short lengths, whereas the ECNC-III showed relatively long length, like CNC-I.

Keywords: Cellulose nanocrystals; Crystallinity; Morphology; Polymorph; Sulfuric acid hydrolysis; TEMPO-mediated oxidation.