A New Family of Renewable Thermosets: Kraft Lignin Poly‐adipates

Abstract

Thermosetting polymeric materials have advantageous properties and are therefore used in numerous applications. In this study, it was hypothesized and ultimately shown that thermosets could be derived from comparably sustainable sub‐components. A two‐step procedure to produce a thermoset comprising of Kraft lignin (KL) and the cross‐linker adipic acid (AdA) was developed. The cross‐linking was activated by means of an acetylating agent comprising isopropenyl acetate (IPA) to form a cross‐linking mixture (CLM). The cross‐linking was confirmed by FTIR and solid‐state NMR spectroscopy, and the esterification reactions were further studied using model compounds. When the KL lignin was mixed with the CLM, partial esterification occurred to yield a homogeneous viscous liquid that could easily be poured into a mold, as the first step in the procedure. Without any additions, the mold was heated and the material transformed into a thermoset by reaction of the two carboxylic acid‐derivatives of AdA and KL in the second step.

Advanced NMR Characterization of Aquasolv Omni (AqSO) Biorefinery Lignins/Lignin‐Carbohydrate Complexes

“…Details about the products yields, their molar mass characterization, and other additional information have been reported in our recent paper. [2]'…”

Sustainable valorisation of renewables through dialkyl carbonates and isopropenyl esters

“…At reflux temperature, the H 2 SO 4 -catalysed reaction of AdA with excess iPAc yielded a cross-linking mixture (CLM) by which lignin was partially esterified to achieve thermoset materials suitable for coatings, with tensile strength in the range of 15-0.33 MPa. 186 Mechanistic studies, carried out by solid-state 13 C MAS NMR and FT-IR, confirmed that both the aliphatic and aromatic hydroxyl groups of lignin were reactive towards the desired transesterification process.…”

Isopropenyl Esters (iPEs) in Green Organic Synthesis

“…In the second paper, the preparation of a diisopropenyl ester was achieved by the Ru‐catalyzed addition of Z ‐aspartic acid to propyne [49] . Intriguingly, the first investigation on the reactivity of di‐iPEs was carried out by some of us for the fabrication of new polymeric materials derived from lignin [240] . The strategy is described in Figure 3.…”

“…[49] Intriguingly, the first investigation on the reactivity of di-iPEs was carried out by some of us for the fabrication of new polymeric materials derived from lignin. [240] The strategy is described in Figure 3.…”