An official website of the United States government
Levoglucosan is a renewable chemical obtained in high yields from pyrolysis of cellulosic biomass, which offers rich functionality for synthetic modification and crosslinking. Here, we report the facile and scalable synthesis of a family of biobased networks from triallyl levoglucosan and multifunctional thiols via UV-initiated thiol–ene click chemistry. The multifunctional thiols utilized in this study can also be sourced from renewable feedstocks, leading to overall high bio-based content of the synthesized levoglucosan networks. The thermomechanical and hydrolytic degradation properties of the resultant networks are tailored based on the type and stoichiometric ratio of thiol crosslinker employed. The Young's modulus and glass transition temperature of levoglucosan-based networks are tunable over the wide ranges of 3.3 MPa to 14.5 MPa and −19.4 °C to 6.9 °C, respectively. The levoglucosan-based thermosets exhibit excellent thermal stability with Td,10% > 305 °C for all networks. The suitability of these resin formulations for extrusion-based 3D printing was illustrated using a UV-assisted direct ink write (DIW) system creating 3D printed parts with excellent fidelity. Hydrolytic degradation of these 3D printed parts via ester hydrolysis demonstrated that levoglucosan-based resins are excellent candidates for sustainable rapid prototyping and mass production applications. Overall, this work displays the utility of levoglucosan as a renewable platform chemical that enables access to tailored thermosets important in applications ranging from 3D printing to biomaterials.
more »
« less
This content will become publicly available on August 12, 2026
Thermosets from Birch Bark: A Holistic Approach Using Green Solvents and Processes
Many recent efforts towards sustainable polymer development use building blocks from renewable biomass feedstocks. However, issues arising from the processes used to extract starting materials from biomass are often overlooked despite the safety and environmental hazards associated with energy-intensive separation processes and solvent utilization. Here, we describe a holistic approach towards using green solvents and processes to synthesize polyester thermosets from birch bark, a waste product from the paper and pulp industry. Betulin, a diol with a pentacyclic ring structure, was extracted from the bark of silver birch trees via reflux boiling using green solvents available from biobased sources. Ethanol and 1:1 ethanol:ethyl acetate mixtures were effective solvents for extraction with additional selectivity achieved via antisolvent precipitation. Betulin-rich extracts containing 62.2-81.5 wt% betulin were produced and directly used to prepare polyester thermosets using one-pot, solventless polycondensations with 100% of the starting materials available from biomass feedstocks. The polymers prepared directly from extracts had comparable properties to those synthesized from pure betulin, suggesting that additional processing steps required to achieve higher purity betulin may not be warranted. Overall, we present an approach to polyester development from betulin-rich birch bark extracts which incorporate green chemistry and engineering principles from feedstock to product.
more »
« less
- Award ID(s):
- 1934368
- PAR ID:
- 10655170
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- ACS Omega
- Volume:
- 10
- Issue:
- 31
- ISSN:
- 2470-1343
- Page Range / eLocation ID:
- 35207 to 35216
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)3D printing is an essential tool for rapid prototyping in a variety of sectors such as automotive and public health. The 3D printing market is booming, and it is projected that it will continue to thrive in the coming years. Unfortunately, this rapid growth has led to an alarming increase in the amount of 3D printed plastic waste. 3D printing processes such as stereolithography (SLA) and digital light projection (DLP) in particular generally produce petroleum-based thermosets that are further worsening the plastic pollution problem. To mitigate this 3D printed plastic waste, sustainable alternatives to current 3D printing materials must be developed. The present review provides a comprehensive overview of the sustainable advances in SLA/DLP 3D printing to date and offers a perspective on future directions to improve sustainability in this field. The entire life cycle of 3D printed parts has been assessed by considering the feedstock selection and the end-of-use of the material. The feedstock selection section details how renewable feedstocks (from lignocellulosic biomass, oils, and animal products) or waste feedstocks ( e.g. , waste cooking oil) have been used to develop SLA/DLP resins. The end-of-use section describes how materials can be reprocessed ( e.g. thermoplastic materials or covalent adaptable networks) or degraded (through enzymatic or acid/base hydrolysis of sensitive linkages) after end-of-use. In addition, studies that have employed green chemistry principles in their resin synthesis and/or have shown their sustainable 3D printed parts to have mechanical properties comparable to commercial materials have been highlighted. This review also investigates how aspects of sustainability such as recycling for feedstock/end-of-use or biodegradation of 3D printed parts in natural environments can be incorporated as future research directions in SLA/DLP.more » « less
-
Abstract Reprocessable and biobased thermosets are prepared from two renewable feedstocks, lignin and polyamine (Priamine 1071). Lignin is oxidized to produce polycarbonyl and further reacts with polyamine to form a crosslinked network of imines. The thermoset materials are formed under heat and pressure in the absence of any catalysts. The mechanical strength and thermal properties of thermosets are tunable by changing feedstock ratios. The dynamic imine crosslinks can be associatively reformed.more » « less
-
Electrochemical conversion of biomass-derived intermediate compounds to high-value products has emerged as a promising approach in the field of biorefinery. Biomass upgrading allows for the production of chemicals from non-fossil-based carbon sources and capitalization on electricity as a green energy input. Amino acids, as products of biomass upgrading, have received relatively little attention. Pharmaceutical and food industries will benefit from an alternative strategy for the production of amino acids that does not rely on inefficient fermentation processes. The use of renewable biomass resources as starting materials makes this proposed strategy more desirable. Herein, we report an electrochemical approach for the selective oxidation of biomass-derived α-hydroxyl acids to α-keto acids, followed by electrochemical reductive amination to yield amino acids as the final products. Such a strategy takes advantage of both reactions at the anode and cathode and produces amino acids under ambient conditions with high energy efficiency. A flow electrolyzer was also successfully employed for the conversion of α-hydroxyl acids to amino acids, highlighting its great potential for large-scale application.more » « less
-
Alternative polymer feedstocks are highly desirable to address environmental, social, and security concerns associated with petrochemical-based materials. Lignocellulosic biomass (LCB) has emerged as one critical feedstock in this regard because it is an abundant and ubiquitous renewable resource. LCB can be deconstructed to generate valuable fuels, chemicals, and small molecules/oligomers that are amenable to modification and polymerization. However, the diversity of LCB complicates the evaluation of biorefinery concepts in areas including process scale-up, production outputs, plant economics, and life-cycle management. We discuss aspects of current LCB biorefinery research with a focus on the major process stages, including feedstock selection, fractionation/deconstruction, and characterization, along with product purification, functionalization, and polymerization to manufacture valuable macromolecular materials. We highlight opportunities to valorize underutilized and complex feedstocks, leverage advanced characterization techniques to predict and manage biorefinery outputs, and increase the fraction of biomass converted into valuable products.more » « less
