Utilization of Lignin-Derived Small Molecules: Epoxy Polymers from Lignin Oxidation Products

A review on lignin-based epoxy resins: Lignin effects on their synthesis and properties

Lignin can be used as a sustainable alternative to bisphenol A (BPA) to prepared lignin-based epoxy resins. Lignin effects including molecular weight, phenolic content, G/S unit ratio and flexible/rigid linkage ratio on epoxy synthesis and performance were summarized comprehensively. The incorporation of lignin with a higher molecular weight would lead to the higher rigidity of epoxy crosslinking network. Higher contents of ether bonds in lignin would provide higher structural flexibility of lignin incorporated epoxy thermosets. Lignin with higher contents of phenolic hydroxyls was more beneficial for improving the reactivity of its epoxy products after glycidylation. Due to the excellent charring capacity of lignin, higher contents of residue char can be produced at higher additions of lignin at high temperatures, while the loss of crosslinking density caused by the increasing lignin addition (especially for the macromolecular lignin) would deteriorate the thermal stability of their thermosets. Several applications of lignin-based epoxy resins were also mentioned based on their mechanical, thermal and chemical properties, such as coatings (with anticorrosion and UV-blocking), adhesives (with highly crosslinking network, excellent mechanical, and thermal properties) and flame retardants (with high charring capability).

Investigation of Charged Small Molecule-Aptamer Interactions with Surface Plasmon Resonance

Investigating the interactions between small, charged molecules and aptamers using surface plasmon resonance (SPR) is limited by the inherent low response of small molecules and difficulties with nonspecific electrostatic interactions between the aptamer, analyte, and sensor surface. However, aptamers are increasingly being used in sensors for small molecule detection in critical areas like healthcare and environmental safety. The ability to probe these interactions through simple, direct SPR assays would be greatly beneficial and allow for the development of improved sensors without the need for complicated signal enhancement. However, these assays are nearly nonexistent in the current literature and are instead surpassed by sandwich or competitive binding techniques, which require additional sample preparation and reagents. In this work, we develop a method to characterize the interaction between the charged small molecule serotonin (176 Da) and an aptamer with SPR using streptavidin-biotin capture and a high-ionic-strength buffer. Additionally, other methods, such as serotonin immobilization and thiol-coupling of the aptamer, were investigated for comparison. These techniques give insight into working with small molecules and allow for quickly adapting a binding affinity assay into a direct SPR sensor.

Exploiting Nature's Most Abundant Polymers: Developing New Pathways for the Conversion of Cellulose, Hemicellulose, Lignin and Chitin into Platform Molecules (and Beyond)

The four most prominent forms of biomass are cellulose, hemicellulose, lignin and chitin. In efforts to develop sustainable sources of platform molecules there has been an increasing focus on examining how these biopolymers could be exploited as feedstocks that support the chemical supply chain, including in the production of fine chemicals. Many different approaches are possible and some of the ones being developed in the authors' laboratories are emphasised.

Biofuels for a sustainable future

Rapid increases of energy consumption and human dependency on fossil fuels have led to the accumulation of greenhouse gases and consequently, climate change. As such, major efforts have been taken to develop, test, and adopt clean renewable fuel alternatives. Production of bioethanol and biodiesel from crops is well developed, while other feedstock resources and processes have also shown high potential to provide efficient and cost-effective alternatives, such as landfill and plastic waste conversion, algal photosynthesis, as well as electrochemical carbon fixation. In addition, the downstream microbial fermentation can be further engineered to not only increase the product yield but also expand the chemical space of biofuels through the rational design and fine-tuning of biosynthetic pathways toward the realization of "designer fuels" and diverse future applications.

Novel lignin-containing high-performance adhesive for extreme environment

The gradual depletion of petroleum is a main challenge restricting the development for the fine chemicals, such as epoxy resin adhesive. In this study, a novel lignin-containing high-performance epoxy resin adhesive is synthesized using lignin as precursor material. Lignin is a unique biomacromolecule with three dimensional network structure, large molecular weight, and aromatic structure. The lignin is simply hydrolyzed and modified by epichlorohydrin to obtain lignin-based epoxy prepolymer. The hydrolysis process effectively reduces the molecular weight and improves the chemical reactivity of lignin, thus increasing the number of modified functional groups and the dispersibility of lignin concurrently. With the introduction of the lignin-based epoxy prepolymers, the shear strength of the adhesive increases obviously and reaches 10.42 MPa, which displays 228% of the shear strength of commercial epoxy resin adhesives. Furthermore, the lignin-containing epoxy resin adhesive still displays excellent mechanical properties in extreme environments, including extreme temperature and high humidity environment.