Aromatics from Lignocellulosic Biomass: A Platform for High-Performance Thermosets

Abstract

Renewable and sustainable thermosets with thermomechanical properties that are equivalent to, or better than, those of petroleum-derived commercial incumbents are desirable to mitigate environmental and human health impacts. Current bioderivable or biobased thermosets typically are aliphatic/cycloaliphatic and lack the robust structural features necessary to generate materials competitive with those made from conventional aromatics such as bisphenol A. Lignocellulosic biomass (LCB) is the most abundant, renewable feedstock for the production of platform aromatic chemicals (e.g., phenolics from lignin, furanics from cellulosics) which are ideal as sustainable, biobased alternatives to petroleum-derived constituents for high-performance applications. This Perspective provides an overview of LCB-derivable aromatic monomers, including epoxies, cyanate esters, vinyl esters, benzoxazines, and cyclic carbonates, and it benchmarks the corresponding materials against commercially available thermosets. Furthermore, green synthesis approaches to minimize environmental impacts, robust processing methods to increase versatility, structure−property relationships to guide materials design, and life-cycle management strategies to improve the recyclability of thermosets are discussed, along with additional avenues to advance the commercial relevance of biobased thermosets. For instance, the positive impacts of the inherent functionality in biobased monomers on toxicity and environmental considerations, as well as opportunities to leverage the synergies between experimental and computational activities, are highlighted.

Estrogenic activity of lignin-derivable alternatives to bisphenol A assessed via molecular docking simulations

“…Bisphenol A (BPA) is one of the most important precursors to an array of polymeric systems, such as epoxy resins, polysulfones, and polycarbonates, among others. [1][2][3][4] These polymeric materials are used extensively in numerous applications, particularly for biomedical and food contact products (e.g., dental cement composites, food containers, infant bottles). 1,[4][5][6] However, BPA is known to leach from polymeric products and can potentially enter the human body.…”

“…5,6,[9][10][11][12][13] The disruption of the endocrine system can lead to severe human health impacts, including diabetes, 14 obesity, 15 cardiovascular diseases, 16 reproductive disorders, 17 and cancer. 2,18 Therefore, several countries have restricted or eliminated BPA use in food contact applications. [19][20][21] In fact, the European Chemicals Agency has listed BPA in its "Candidate List of Substances of Very High Concern".…”

“…1,2,4,[24][25][26][27][28][29][30][31][32][33][34][35][36] Bulk lignin mainly consists of three subunits: p-hydroxyphenyl (H) (no methoxy groups on the aromatic ring), guaiacyl (G) (one methoxy group on the aromatic ring [monomethoxy]), and syringyl (S) (two methoxy groups on the aromatic ring [dimethoxy]) groups. 1,2,4,33,37 The compositions of these units can vary as a function of biomass source: sowoods contain a majority of G units, hardwood include a mixture of G and S units, and grasses contain a mixture of H, G, and S units. 2,4,37 Additionally, the structural heterogeneity 38 and limited reactivity 39 of bulk lignin can lead to materials with inconsistent properties, and the odor and dark color of bulk lignin limit its use to lower-value applications.…”

“…1,2,4,33,37 The compositions of these units can vary as a function of biomass source: sowoods contain a majority of G units, hardwood include a mixture of G and S units, and grasses contain a mixture of H, G, and S units. 2,4,37 Additionally, the structural heterogeneity 38 and limited reactivity 39 of bulk lignin can lead to materials with inconsistent properties, and the odor and dark color of bulk lignin limit its use to lower-value applications. 2,38 Several methods, such as pyrolytic, catalytic, and enzymatic depolymerization, can break down bulk lignin into smaller, well-dened aromatics with useful moieties, particularly phenolic hydroxyl and methoxy units.…”

Exploring the Electronic Properties of Extended Benzofuran‐Cyanovinyl Derivatives Obtained from Lignocellulosic and Carbohydrate Platforms Raw Materials

“…Utilization of biomass as raw materials to produce the conjugated structure of OSC can liberate from the reliance on fossil resource and so allow the development of renewable materials. Although polyfunctional conjugated synthons, derived from lignocellulosic biomass, [1,2,3,4] represent potential raw materials for the development of OSC materials, alternatives for using these bio‐sourced molecules have so far been rarely developed [5,6] . Lignin is a very important sustainable feedstock strongly worked for the development of methoxy‐benzaldehyde derivatives such as vanillin and syringaldehyde [7,8,9,10] .…”