Production and Surface Modification of Cellulose Bioproducts

Abstract

Petroleum-based synthetic plastics play an important role in our life. As the detrimental health and environmental effects of synthetic plastics continue to increase, the renewable, degradable and recyclable properties of cellulose make subsequent products the "preferred environmentally friendly" alternatives, with a small carbon footprint. Despite the fact that the bioplastic industry is growing rapidly with many innovative discoveries, cellulose-based bioproducts in their natural state face challenges in replacing synthetic plastics. These challenges include scalability issues, high cost of production, and most importantly, limited functionality of cellulosic materials. However, in order for cellulosic materials to be able to compete with synthetic plastics, they must possess properties adequate for the end use and meet performance expectations. In this regard, surface modification of pre-made cellulosic materials preserves the chemical profile of cellulose, its mechanical properties, and biodegradability, while diversifying its possible applications. The review covers numerous techniques for surface functionalization of materials prepared from cellulose such as plasma treatment, surface grafting (including RDRP methods), and chemical vapor and atomic layer deposition techniques. The review also highlights purposeful development of new cellulosic architectures and their utilization, with a specific focus on cellulosic hydrogels, aerogels, beads, membranes, and nanomaterials. The judicious choice of material architecture combined with a specific surface functionalization method will allow us to take full advantage of the polymer's biocompatibility and biodegradability and improve existing and target novel applications of cellulose, such as proteins and antibodies immobilization, enantiomers separation, and composites preparation.

Keywords: applications; biomaterials; bioproducts; cellulose; surface functionalization.

Figure 1

Intra-chain and inter-chain hydrogen bonding in cellulose.

Figure 2

Schematic of cellulose dissolution.

Figure 3

pH sensitive cotton fabrics prepared by covalent immobilization of Nitrazine Yellow (NY) containing hybrid matrix on the textile surface. Reprinted from ref. [111] © 2021 with permission from Elsevier.

Figure 4

Photographs of superabsorbent cellulose/carboxymethylcellulose (CMC) hydrogels: (a) original hydrogel, (b) swollen hydrogel, (c) dried hydrogel, and (d) hydrogel after swelling in NaCl solution for a week. Reprinted from ref. [118] © 2021 with permission from Elsevier.

Figure 5

Preparation of cellulose aerogel monoliths. (a) cellulose solution in glass molds, (b) gelated cellulose solution, (c) regenerated cellulose hydrogel, (d) supercritical dried cellulose aerogel monoliths (aerocellulose monoliths), (e) surface modified and non-modified cellulose aerogels in dye solutions (the non-modified samples have not adsorbed dye from the solution and the aerogels have retained their original color. The surface modified samples have adsorbed dye from the solution, and the solution has become clear, and aerogels have become dark blue due to dye adsorption), and (f) SEM micrographs of an aerocellulose monolith cross-section.

Figure 6

Cellulose beads (CBs) prepared by dropping technique. (a) CBs in a coagulation bath, (b) SEM micrograph of a CB, and (c) SEM micrograph of a CB cross-section.

Figure 7

Production of non-porous and porous cellulose films via casting approach. (a) Casting cellulose solution in a glass mold, (b) regenerated and plasticized cellulose hydrogel, (c) hot-pressed flexible cellulose films, and porous cellulose films (d) free surface and (e) fracture surface (Figure 7d,e were reprinted from Ref. [16] with permission from wileyonlinelibrary.com).

Figure 8

Different types of nanomaterials: (a) cellulose nanofibrils (CNFs) obtained from mechanical disintegration of pinewood cellulose, (b) cellulose nanocrystals (CNCs) obtained from sulfuric acid hydrolysis of filter paper, and (c) bacterial cellulose obtained from culture of Komagataeibacter xylinus. Reprinted, (a) from ref. [182] © 2021 with permission from Elsevier, (b) from ref. [181] as distributed by Creative Common CC BY license, (c) from ref. [183] © 2021 with permission from Elsevier.