Title: From order to chaos: Case studies of cellulose and lignin materials

Abstract

Wood is a natural bio-composite that is composed of primarily cellulose (~40%), hemicellulose (~30%) and lignin (~30%). The former is a partially crystalline polysaccharide composed of glucose units which reinforce the matrix made of hemicellulose and lignin. Although cellulose-derived materials find numerous applications, they must coexist with hydrophobic polymers, which can be challenging due to the hydrophilic character of cellulose. A versatile way to modify cellulosic materials is through the physical adsorption of colloidal nanoparticles synthesized in water, called nanolatexes. Their synthesis is based on the combination of the reversible addition-fragmentation chain transfer (RAFT) polymerization with polymerization-induced self-assembly (PISA). The bridging of these techniques results in the formation of amphiphilic di-block copolymers which self-assemble in water forming a variety of morphologies. These nanolatexes have been used to investigate the key parameters that govern their adsorption on cellulosic surfaces [1] as well as in the preparation of nanocomposites with low content of nanolatexes [2]. Additionally, nanolatexes are known to be highly versatile in terms of morphological transitions. Hence, it was shown that by tuning the chemistry of the RAFT agent as well as the polymers used, different morphologies were achieved directly influencing the targeting application [3, 4].

Lignin is the most abundant aromatic biopolymer that has puzzled the research community for decades as its native structure is still unknown. However, that has not prevented us from preparing functional lignin-based materials by using the so-called technical lignins, i.e., modified by-products of the pulping process. Versatile materials have been made from lignin by precipitating it in an anti- solvent, hence, producing nanoparticles (LNPs). Although LNPs have been primarily prepared from technical lignins, native-like fractions directly extracted from wood with mild processes give another perspective on the structure-property profile of such nanoparticles [5]. Finally, LNPs prepared from technical lignin can be degraded through ozonolysis, thus closing the loop of lignin materials, starting from their precipitation to their decomposition with an industrially relevant process.

References

1. A. E. Alexakis. et al., Journal of Colloid and Interface Science, 634, 2023, 610–620.
2. A. E. Alexakis§, Å. Jerlhagen§, et al., Macromol. Chem. Phys., 2023, 224, 2200249.
3. A. E. Alexakis. et al., RSC Polym. Chem., 2023, 14, 2308–2316
4. A. E. Alexakis, E. Malmström, Macromol. Chem. Phys., manuscript under review
5. I. Sapouna, et al., Industrial Crops and Products, 206, 2023, 117660.
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