Effect of Cellulose Nanocrystals on the Coating of Chitosan Nanocomposite Film Using Plasma-Mediated Deposition of Amorphous Hydrogenated Carbon (a–C:H) Layers

Torben Schlebrowski,Zineb Kassab,Christian B Fischer,Stefan Wehner,Mounir El Achaby

doi:10.3390/c6030051

Abstract

The substitution of petroleum-based polymers with naturally derived biopolymers may be a good alternative for the conservation of natural fossil resources and the alleviation of pollution and waste disposal problems. However, in order to be used in a wide range of applications, some biopolymers’ properties should be enhanced. In this study, biocompatible, non-toxic, and biodegradable chitosan (CS) film and CS reinforced with 10 wt% of cellulose nanocrystals (CN–CS) were coated with amorphous hydrogenated carbon layers (a–C:H) of different thickness. To investigate the effect of the nano-reinforcement on the a–C:H layer applied, mild radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) was used to coat the CS and its CN–CS bio-nanocomposite film. Both the surface characteristics and the chemical composition were analyzed. The surface morphology and wettability were examined by ex-situ atomic force microscopy (AFM) and contact angle measurements (CA), respectively. Hereby, the relationship between sp2/sp3 ratios on a macroscopic scale was also evaluated. For the investigation of the chemical composition, the surface sensitive synchrotron X-ray radiation techniques near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) as well as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) were used.

Highlights

Biopolymers are considered potential substitutes for conventional plastic materials because of their main advantages, including non-toxicity, biodegradability, wide availability, and biocompatibility; some of their properties must be improved to position them as materials that can compete with petroleum-based materials [1,2]
The results of the 100 nm amorphous hydrogenated carbon layers (a–C):H layer again do not change compared to the 50 nm sample, even if the intensity is somewhat lower over the entire spectrum
It must be mentioned that the chemical systems for the present 50 nm samples are different. Both depositions are comparable only after reaching a layer thickness of 100 nm, which means that the growth of the a–C:H layer will gradually level out and become more and more the same after completion of the intermediate layer. Both pure CS film and cellulose nanocrystals (CN–CS) nanocomposite film were coated with stable a–C:H layers of 50 and 100 nm thickness

Summary

Introduction

Biopolymers are considered potential substitutes for conventional plastic materials because of their main advantages, including non-toxicity, biodegradability, wide availability, and biocompatibility; some of their properties must be improved to position them as materials that can compete with petroleum-based materials [1,2] One of these biopolymers is chitosan (CS). CS is a natural cationic linear biopolymer and deacetylated derivative of chitin composed of β-(1,4)-2-acetamido-2-deoxy-D-glucose and β-(1,4)-2-amino-2-deoxy-D-glucose units [3] It is one of the most important natural polymers because of its non-toxicity, antimicrobial activity, and excellent film-forming properties; without forgetting the disadvantages, it has a wide range of applications such as food, agriculture, biomedicine, pharmacy, packaging industries, materials science and wastewater treatment [1]. C 2020, 6, 51 to expand the fields of application of CS, the unfortunate mechanical and surface properties of CS must be enhanced by combining efficient nano-reinforcement and surface treatment technologies [2,3].

Methods

Results

Conclusion