In Situ Lignin Modification Enabling Enhanced Interfibrillar Interactions in Lignocellulosic Nanomaterials toward Structural Applications

Abstract

Lignocellulose nanopaper (LNP) assembled from lignocellulose nanofibrils (LCNFs) is an emerging eco-friendly structural material applicable to a variety of fields. Lignin serves as a crucial functional component in the LNP matrix; however, it negatively affects the interfacial hydrogen-bonding behaviors among LCNFs and consequently the inferior mechanical performance of LNP. In this study, a mild ozone-oxidation strategy was used to modify lignin macromolecules in situ without significant degradation of carbohydrate polymers (i.e., cellulose and hemicellulose) in LCNFs whereupon the interfacial hydrogen-bond energy was dramatically improved in the assembly and deformation process of LNP as validated by molecular dynamics simulation. Consequently, the lignin-modified LNP exhibited significantly enhanced tensile strength (from 83 to 140 MPa) and toughness (from 1.9 to 7.1 J/m 3 ), which even surpassed those of conventional cellulose nanopaper. Benefiting from the well-preserved lignocellulosic structure, lignin-modified LNP maintained its inherent favorable water and thermal stability and intriguing optical performance, which supported our developed LNP to be a multifunctional structural material for diversified fields, for example, flexible electronic applications. Additionally, the estimated production cost for our developed LNP was approximately half of that for conventional cellulose nanopaper due to its significantly lower resource inputs such as the material, water, and energy. Overall, our study provides a site-specific macromolecular modulation strategy for the economically and environmentally feasible fabrication of highperformance lignocellulosic nanomaterials toward advanced structural applications.

Sulfated lignocellulose nanofibril supported flower-like BiOBr with oxygen vacancies towards absorption–photocatalytic synergetic removal of organic pollutants

“…, stretching vibrations of lignin CC at 1601 cm −1 and 1507 cm −1 , and lignin aromatic ring O–CH 3 at 1457 cm −1 ). 58 For SLCNFs and BiOBr/SLCNF, the asymmetric SO and the symmetric C–O–S vibrations of sulfate groups were noted at around 1250 cm −1 and 802 cm −1 , respectively. 59 In addition, NH 4 + deformation vibration at 1427 cm −1 was observed owing to the presence of ammonium salt of sulfate ester.…”

Mechanically strong, self‐healing and pH‐responsive lignocellulose nanofibril‐based hydrogels towards drug delivery applications

“…When the introduction of CLCNF in the hydrogel, the maximum thermal degradation temperature rises from 304.95 to 312.87°C; the third stage is 360-480 ℃, mainly the decomposition of cellulose and lignin; when temperatures rise to 480°C, weight loss may be attributed to the carbon formation reaction. The presence of CLCNF in the hydrogel system improved the thermal stability of the hydrogel [33]. At a temperature of 700°C, the residual weight was found to be as low as 15.4 wt%, suggesting that combustion is an effective method for disposing of hydrogel waste [45].…”

“…Lignin is a kind of complex polyphenol, containing rich groups such as aliphatic groups, aromatic hydroxyl, methoxy and carbonyl [29,30]. Lignin contained in LCNF can provide more active sites [31] and better interaction force between the carrier and drug molecules (electrostatic action, π-π superposition and hydrogen bonding [21]), thus prolonging the release time of the drug [14,32], which is of great signi cance to improve the interaction force between the carrier and the drug and enhance the mechanical properties of the hydrogel [33,34]. Antti et al [35] also con rmed that the interaction between adsorbents and aromatic and phenolic groups of LCNF have higher adsorption performance than CNF; Rojo et al found that a small amount of lignin improved the mechanical properties of the hydrogel due to stress transfer between CNF [34].…”