Regulating Lignin-Based Epoxy Vitrimer Performance by Fine-Tuning the Lignin Structure

Abstract

Lignin is the second most abundant lignocellulosic biomass, and as a natural polymer, it shows great potential in preparing functional materials to meet the demand for green/ sustainable development. Unfortunately, the inherent heterogeneity of lignin largely limits its applications. Furthermore, the effect of the lignin structure on the performance of the final materials has seldom been investigated. In this work, a totally biobased dynamic cross-linked vitrimer with up to 70% lignin content was successfully prepared from epoxidized fractionated lignin and sebacic acid without additional chemical modifications. The lignin structure effect on the performance of the resultant lignin-based epoxy vitrimers (LEVs) was systematically investigated. The experimental results show that the phenolic hydroxyl content and the ratio of flexible to rigid linkages in lignin have strong correlations with the tensile strength, toughness, self-repair ability, and reprocessability of the resultant LEVs. Meanwhile, the molecular weight and the S/G ratio of lignin show strong correlations with the thermal properties of the resultant materials. This study not only presents a fundamental study regarding the relationships between lignin properties, and the resultant LEVs have great potential applications as advanced packaging materials for light-sensitive commodities due to the inherent UV resistance of lignin.

High‐Performance Vitrimeric Benzoxazines for Sustainable Advanced Materials: Design, Synthesis, and Applications

“…[ 28 ] Many epoxy vitrimers have since been reported, featuring excellent properties. [ 29–77 ] Other reported vitrimers are based on polybutadienes, [ 78–82 ] polyurethanes, [ 83–99 ] polyhydroxyurethanes, [ 100,101 ] polyurethane urea, [ 102,103 ] polyesters, [ 104–115 ] polycarbonates, [ 116 ] and polyimides. [ 117,118 ] These materials have low‐to‐medium‐to‐high glass transition temperatures, with polyimide vitrimer achieving T g of 274 °C and a 5% weight loss temperature of 429 °C.…”

Biobased Transesterification Vitrimers

“…Tang et al prepared lignin‐based epoxy vitrimers from fractionated lignin and sebacic acid. [ 61 ] The fractionated lignin was then epoxy‐modified using epichlorohydrin to produce glycidyl ethers of lignin, which was subsequently reacted with sebacic acid. The epoxy vitrimers had a Young's modulus above 1 GPa.…”

Synthesis of Renewable, Recyclable, Degradable Thermosets Endowed with Highly Branched Polymeric Structures and Reinforced with Carbon Fibers

“…Bio-based thermosets that consist of biogenic carbons can be a solution because their use can reduce fossil fuel consumption and the carbon footprint . In particular, with the help of dynamic covalent chemistry, they are reprocessable and chemically recyclable; thus, they constitute bio-based covalent adaptable networks. , A variety of biomasses have been exploited for this purpose: vegetable oils − (including vanillin, − eugenol, , and cardanol , ), natural acids, − flavonoids, , and biopolymers, for example, polysaccharides, natural resins, and lignins. − Most of them contain β-hydroxy ester bonds that are commonly derived from epoxide, promoting transesterification due to the presence of free hydroxyl groups adjacent to the esters . Moreover, dynamic covalent bonds such as imine, disulfide, hindered urea, , acetal, boronic ester, and carbamate have been applied to build renewable dynamic networks.…”