The Self-Assembly of Lignin and Its Application in Nanoparticle Synthesis: A Short Review

Abstract

Lignin serves as a significant contributor to the natural stock of non-fossilized carbon, second only to cellulose in the biosphere. In this review article, we focus on the self-assembly properties of lignin and their contribution to its effective utilization and valorization. Traditionally, investigations on self-assembly properties of lignin have aimed at understanding the lignification process of the cell wall and using it for efficient delignification for commercial purposes. In recent years (mainly the last three years), an increased number of attempts and reports of technical-lignin nanostructure synthesis with controlled particle size and morphology have been published. This has renewed the interests in the self-assembly properties of technical lignins and their possible applications. Based on the sources and processing methods of lignin, there are significant differences between its structure and properties, which is the primary obstacle in the generalized understanding of the lignin structure and the lignification process occurring within cell walls. The reported studies are also specific to source and processing methods. This work has been divided into two parts. In the first part, the aggregation propensity of lignin based on type, source and extraction method, temperature, and pH of solution is discussed. This is followed by a critical overview of non-covalent interactions and their contribution to the self-associative properties of lignin. The role of self-assembly towards the understanding of xylogenesis and nanoparticle synthesis is also discussed. A particular emphasis is placed on the interaction and forces involved that are used to explain the self-association of lignin.

A Simple Method to Synthesize Lignin Nanoparticles

“…Most of the methods involve the self-assembly of lignin, which, in turn, is affected by the nature or type of the solvent, type of noncovalent interaction, the structure of technical lignin, the extent of condensation, and also by solvent-lignin-antisolvent interactions [11,12]. Therefore, different approaches for the synthesis of lignin nanoparticles also provide an excellent platform for the study of inter-and intramolecular interactions of technical lignins, their solution structure, and their solvent-solute interactions [13,14]. Several reviews on lignin nanoparticle synthesis and its underlying processes have already addressed the issue in detail [7,11,13].…”

“…Therefore, different approaches for the synthesis of lignin nanoparticles also provide an excellent platform for the study of inter-and intramolecular interactions of technical lignins, their solution structure, and their solvent-solute interactions [13,14]. Several reviews on lignin nanoparticle synthesis and its underlying processes have already addressed the issue in detail [7,11,13]. Lignin nanoparticles can have applications in agriculture, biocomposites, biomedical science, coatings, and many other fields [6,7].…”

“…Lignin nanoparticles can have applications in agriculture, biocomposites, biomedical science, coatings, and many other fields [6,7]. The number of approaches used for lignin nanoparticles from a solution either involve precipitation from a solvent using some sort of antisolvent (involving solvent-solute-antisolvent interactions), or atomization and droplet processing (using the one drop, one particle approach) [13]. In our previous study, we reported a method using an ultrasonic nebulizer [15], which needed complex assembly and instrumentation.…”

Vegetable Additives in Food Packaging Polymeric Materials

“…Regarding the nanocellulose, there some particularities compared with other artificial nanoparticles: In the case of carbon nanoparticles or nanoclays, the mechanical constraining of polymer chains [99], and surface/polymer interaction (with formation of layer of perturbed macromolecules around nanoparticles [100]) are supposed to be responsible for the beneficial effect of nanoparticles on the mechanical properties. In the case of nanocellulose, different mechanisms allow the nanocellulose to influence and enhance the polymer properties [101], i.e., the formation of a network of long nanoscale fibers [101]; the interaction between nanoparticles/nanofibrils, which is controlled not only by Van der Waals forces but also by strong hydrogen bonds [102,103]; and also the adhesion to the polymer matrix, which is dominated by hydrogen bonding [104,105]. Different to carbon nanoparticles, nanocellulose fibrils do not form clusters but percolation networks [106], which have a positive effect on the strength of the composites [107].…”

Bio-Based Composites from Industrial By-products and Wastes as Raw Materials

“…This heterogeneous biopolymer is a by-product of biorefineries that process plant biomass to produce fuels and chemicals, but also a waste of the pulp and paper industries. Generally, most of the lignins are burned to generate heat and electricity, but has also gained increased attention in other application areas such as pharmacology (Spiridon, 2018), as lignin nanostructure for possible applications in UV protection and biomedical applications (Mishra & Ekielski, 2019), or bioplastic and bio-composites (J. Yang, Ching, & Chuah, 2019).…”