Using Cellulose Nanocrystal as Adjuvant to Improve the Dispersion Ability of Multilayer Graphene in Aqueous Suspension.

Haiqiao Zhang,Huiling Dong,Feng Yang,Yan Wu,Jilei Zhang,Yuqing Bian,Xuqin Xie,Huanliang Jia

doi:10.3389/fbioe.2021.638744

Abstract

Cellulose nanocrystal (CNC) has been applied in various fields due to its nano-structure, high aspect ratio, specific surface area and modulus, and abundance of hydroxy groups. In this work, CNC suspensions with different concentrations (0.4, 0.6, and 0.8%) were used as the adjuvant to improve the dispersion ability of multilayer graphene (MLG) in aqueous suspension, which is easy to be aggregated by van der Waals force between layers. In addition, N-methyl-2-pyrrolidone, ethanol, and ultrapure water were used as control groups. Zeta potential analysis and Fourier transform infrared spectroscopy showed that the stability of MLG/CNC has met the requirement, and the combination of CNC and MLG was stable in aqueous suspension. Results from transmission electron microscopy, Fourier transform infrared spectroscopy, and absorbance showed that MLG had a better dispersion performance in CNC suspensions, compared to the other solutions. Raman spectrum analysis showed that the mixtures of 1.0 wt% MLG with 0.4% CNC had the least defects and fewer layers of MLG. In addition, it is found that CNC suspension with 0.8% concentration showed the highest ability to disperse 1.0 wt% MLG with the most stable performance in suspension. Overall, this work proved the potential application of CNC as adjuvant in the field of graphene nanomaterials.

Highlights

Graphene nanomaterials have been widely used as electrode materials for supercapacitors (Ouyang et al, 2013) and in composites with enhanced electrical (Gao et al, 2013), mechanical (Zhang et al, 2012), and thermal (Shahil and Balandin, 2012) properties because of their excellent properties
After 135 days, some of the alcohol in samples 9 and 10 (MLG/ethanol) evaporated, leaving a few circles of black multilayer graphene (MLG) on the inner wall of the sample bottles. This result showed that CNC at an appropriate concentration can be used as an adjuvant to improve the dispersion ability of MLG in aqueous suspension
The zeta potential and Fourier transform infrared spectroscopy (FTIR) results show that the stability of MLG precipitation occurred in sample 2 (MLG/CNC) meets the requirement and the combination of CNC and ball-milled MLG is stable in aqueous suspension

Summary

INTRODUCTION

Graphene nanomaterials have been widely used as electrode materials for supercapacitors (Ouyang et al, 2013) and in composites with enhanced electrical (Gao et al, 2013), mechanical (Zhang et al, 2012), and thermal (Shahil and Balandin, 2012) properties because of their excellent properties. The current method of dispersing graphene nanomaterial into a matrix is to disperse it in an aqueous surfactant solution first (Lotya et al, 2010). This is because the surfactant molecules attach onto the graphene nanomaterial surface through electrostatic repulsion or intermolecular forces, resulting in the uniform and high concentration dispersion of graphene nanomaterial in the solution. We demonstrated an approach to disperse multilayer graphene (MLG) in water with the cellulose nanocrystal (CNC) as adjuvant (Wu et al, 2019b). We demonstrated an approach to disperse MLG in water with the sulfuric acid hydrolysis CNC as adjuvant. Through comparative experiments, the influence of CNC suspensions with different concentrations as adjuvant on the dispersion ability of MLG in water was evaluated

MATERIALS AND METHODS

RESULTS AND DISCUSSION

DATA AVAILABILITY STATEMENT