Schedule

While plastic pollution threatens ecosystems and human health, the use of plastic products continues to increase. To limit the harm of mismanaged plastic, plastic products should be designed to inherently reduce their environmental impacts by optimizing material efficiency and minimizing environmental persistence. Achieving this requires developing design strategies for plastic products informed by realistic measures of how plastics behave in the environment. Foaming biodegradable bioplastics (i.e., introducing microstructural pores into the material) was hypothesized to achieve this objective. To test this hypothesis, the marine biodegradation of novel cellulose diacetate (CDA) foams of varying relative density was evaluated in a continuous flowing seawater system. After 36 weeks, low-density CDA foams lost 65–70% of their mass, while equivalent polystyrene foams persisted with no change in mass. Surface area-to-volume ratio was shown to be a control of the mass loss rate. A preliminary structure-property relationship for predicting the degradation rate of the foams was determined. Using material indices and value functions, we found that CDA foams could be the favorable choice of material for food-packaging applications with potential benefits to society worth hundreds of millions of dollars annually by switching from PS to CDA foams. 

We present an efficient approach for the depolymerization of vinyl polymers synthesized via conventional radical polymerization. By incorporating low mol % phthalimide ester-containing monomers during the polymerization process, colorless and transparent polymers closely resembling unfunctionalized poly(methyl methacrylate) (PMMA) or polystyrene (PS) are obtained, which can achieve >95% reversion to monomer. Notably, our catalyst-free bulk depolymerization method exhibits exceptional efficiency, even for high-molecular-weight polymers, including ultrahigh-molecular-weight (106–107 g/mol) PMMA, where near-quantitative depolymerization is achieved. This approach yields polymer byproducts of significantly lower molecular weight, distinguishing it from bulk depolymerization methods initiated from chain ends. Furthermore, we extend our investigation to polymer networks, demonstrating high extents of depolymerization. This depolymerization strategy offers promising opportunities for the development of sustainable polymethacrylate materials. 

Crosslinking polymer networks with reversible bonds imbues materials with unique properties such as self-healing, enhanced viscoelasticity, and the ability to be recycled and reprocessed. These properties have been demonstrated to be dictated by the thermodynamics and kinetics of the crosslinking chemistry. This talk will highlight how our group has explored tuning properties in reversible networks using small molecules that interact and compete with the crosslink chemistry, thereby enabling access to a range of properties from a single polymer network. 

Engineering plastics based on step-growth polymerization such as poly(ethylene terephthalate) (PET), polyamides (PA), polyurethanes (PU), polycarbonate (PC), and polyimide (PI) comprise ~30% of the global plastic production. The catalytic deconstruction is one of the major paths for chemical recycling of step-growth polymers. Although there has been progress on their chemical recycling especially PET, most step-growth polymers are not recycled because of the difficulty in depolymerization to pure building blocks especially from mixed waste in an energy efficient manner. Here, we have developed a tailored organocatalyst to enable low energy depolymerization pathways for step-growth polymers. Our catalyst allows glycolysis or aminolysis of PET, PA, PU, PC, PI, and their multiple mixture at moderate temperature with high yield. A wide range of post-consumer plastics waste, such as bottles, packaging, foam, carpet, etc. is readily deconstructed into monomers with high efficiency. The Life Cycle Assessment indicates that the reproduction of various engineering plastics from the deconstructed monomers will result in a significant reduction in greenhouse gas emissions (82-95% reduction) and energy input (68-94% reduction). Furthermore, we have developed a path to deconstruct those step-growth polymers to selective length of oligomers. We have utilized those deconstructed building blocks to synthesize upcycled polymers, and the upcycled polymers can be further deconstructed to reusable building blocks. Such plastic upcycling path contributes to establishing new circular economy of polymers. This presentation will update our progress on chemical deconstruction of step-growth polymers and their upcycling toward circularity. 

Single-use plastics such as polyolefins provide safe packaging for water, food, and medicine, and provide materials for a variety of consumer products. The massive consumption of these materials has led to unsustainable accumulation of plastic waste in landfills and the environment, causing harm to the ecosystem and human health. Mechanical recycling is one option to keep plastic materials in circulation after use; however, only a small fraction of plastic waste is mechanically recycled due to difficulty of separations, high cost of remanufacturing, and low product quality compared to virgin polymers. Chemical recycling is an alternative which can convert waste plastics back into their original chemical building blocks. Heterogeneous catalysts can reduce the energy required to selectively deconstruct polyolefins into hydrocarbons suitable as fuels, chemicals, and monomers. Emerging low-temperature catalytic methods include hydrogenolysis and hydrocracking, metathesis-based deconstruction using sacrificial solvents, and tandem hydrogenolysis/aromatization. The scalability of these methods is limited by the high cost of reactants, the requirement for high pressure molecular hydrogen or solvents, the need for separations, and the high cost of catalytic materials. This talk will start by discussing advances in the catalytic depolymerization of waste plastics via hydrogenolysis and hydrocracking, followed by progress in hydrogen-free depolymerization pathways. The talk will close with a discussion on emerging frameworks for the chemical recycling of mixed and contaminated plastics and an outlook on remaining technical challenges as well as economic and environmental considerations in polymer upcycling, redesign, and circularity. 

The urgent environmental challenges posed by non-renewable resource depletion, harmful manufacturing processes, and persistent plastic waste necessitate innovative approaches in polymer science. Biopolymers and biomatter offer promising solutions, combining renewability and biodegradability to reduce environmental impact across a material's lifecycle. In this talk, we will discuss recent efforts in utilizing biopolymers to engineer sustainable materials with tailored performance, focusing on seaweed-based adhesives and bacterial cellulose networks.

We introduce a seaweed adhesive capable of effectively binding wood particles through hot pressing, offering an eco-friendly alternative to conventional formaldehyde-based resins used in engineered wood panels. Our findings demonstrate that increasing the concentration of seaweed binder not only improves the flexural strength of the biocomposites but also enhances water resistance and flame retardancy. This advancement contributes to reducing the environmental footprint of construction materials while maintaining or improving performance.

In parallel, we investigate the fundamental properties of bacterial cellulose (BC) - a high molecular weight, highly crystalline biopolymer produced by bacteria - focusing on its transition from colloidal to solid state. By applying treatments like deep eutectic solvents, we modify the fiber charge and degree of defibrillation of BC, significantly influencing the rheology and stability of the system. Incorporating other biopolymers and organic molecules, we develop composite printable polymer networks that allow precise control over mechanical properties in both hydrogel and solid states. This enables the fabrication of 3D-printed structures with tailored material behavior, expanding the potential applications of BC-based materials.

The discussed avenues point to a framework for engineering sustainable materials through biopolymer manipulation. The common thread lies in understanding and controlling the structure-property relationships inherent in biomatter systems to achieve desired material characteristics. 

Synthetic and natural polyesters and polysaccharides have emerged as promising environmentally friendly alternatives to petroleum-derived polymeric fibers and films, due to their abundance and biodegradability. However, large-scale applications of these biopolymers remain constrained by high production costs and inferior performance compared to state-of-the-art synthetic systems. For instance, polyesters often exhibit low thermal stability and premature degradation of ester linkages during heat-based reprocessing, hindering recyclability and limiting their use to expensive, single-use alternatives for plastics and textiles. Conversely, while polysaccharides offer high thermal stability and inherent flame retardancy—advantageous for performance textiles and coatings—they present challenges in thermoforming and other large-scale thermal extrusion processes. Here, we discuss how to address these limitations by advancing polymer backbone design and scalable processing strategies to enhance the properties of biodegradable polyesters and polysaccharides. We introduce rapid and versatile polymerization and co-polymerization strategies, utilizing two-phase reactions such as interfacial polymerization and emulsion methods for facile polymer separation. We discuss how transport and reaction kinetics can be leveraged to control the polymer backbone structure and final macromolecular chain dynamics, in turn enabling tailored thermal and mechanical properties. We further explore how copolymerization of polyesters and polysaccharides can affect thermal stability and improve processability. Key factors such as backbone chemistry, molecular weight, and polymer architecture are examined for their influence on thermal behavior and mechanical performance. Last, we also highlight promising processing pathways for these polymers, including their integration in pilot-scale production of films and fiber finishes. By developing scalable synthesis routes and deepening our understanding of the structure-property-processing relationships in these systems, we aim to create sustainable biopolymer alternatives that reduce costs, enhance thermomechanical properties, and enable large-scale deployment. 

Plastics are a global challenge. Society is highly dependent upon plastics to add value to everyday life, however, the end-of-life products are highly problematic, especially when they enter into our waterways, crowd our waste streams, and produce nanoplastics that are released into the environment. Sustainable materials design, synthesis, and implementation are more important than ever for eliminating the environmental effects of plastic waste. Sugars are a powerful class of small molecules to use in the design of polymeric materials. The combination of functional group-rich molecules and sugar chemistry has been well explored over the last 50 years affords a toolbox for monomer synthesis. This vast array of synthesized monomers allows for diverse types of polymerization to be performed. Upon the synthesis of linear polymers and networks, thermal and mechanical characterization has been conducted to assess these materials for various applications. 

Soft materials provide molecular mechanisms that allow the design of products capable of achieving sustainability goals (green chemistry and circular economy). Unique reversible and irreversible interactions that create flexible molecular architectures provide structural resilience and adaptation in various environments. These systems under dynamic equilibria offer customized product performance and enable circular economic models of reuse. This presentation will discuss examples of noncovalent derivatization and photo crosslinked polymer matrices as bioinspired illustrations of commercially relevant technologies that are consistent with the 12 principles of green chemistry. 

Polyurethanes are the 6th most widely produced type of plastic globally, but they pose significant health and safety risks due to isocyanate toxicity and non-biodegradability. The cross-linked structure also presents challenges for recycling. Efforts to address these issues include the development of biobased feedstocks. However, it is essential to address the toxicity of diisocyanates regardless of their source. New, more environmentally friendly methods for producing polyurethanes without isocyanates have emerged, broadening their eco-friendly potential. These new methods involve two key approaches. The first is polyaddition reactions between bis-cyclic carbonates and diamines, which yield polyhydroxyurethanes (PHUs). The second approach is transurethane polycondensation between bis-carbamates and diols, resulting in polyurethanes with properties similar to traditional diisocyanate-based materials.

Nevertheless, developing biodegradable, cost-effective, large-scale non-isocyanate polyurethanes (NIPUs) remains challenging. This requires addressing the trade-offs between biodegradability and stability, matching the performance of conventional polyurethanes, integrating biobased feedstocks, and achieving closed-loop recyclability. Additionally, reaching a high molecular weight of PHU is crucial. Exploring NIPU applications in flexible foams, coatings, adhesives, and elastomers presents opportunities for innovation. The Pilla research group has made noteworthy strides in creating biobased NIPUs and foams using lignin and post-consumer plastic precursors. They have also introduced chemical linkages capable of dissociation post-synthesis for chemical recycling. This presentation highlights some of the innovations facilitated by the Pilla Research Group in developing NIPUs and foams. 

Furan-based building blocks for chemicals and polymers can be obtained from the processing of cellulose and hemicellulose. New families of furan-based thermosetting materials will be presented. By coupling furfuryl amine (FA) with aldehydes and di-aldehydes, di-furan di-amine (DFDA) and terra-furan tetra-amine (TFTA) molecules, containing two or four furan rings, respectively, can be formed. These amines serve as the basis for epoxy and benzoxazine thermosetting systems with unique properties. Compared to traditional epoxies, furan-based epoxy amine systems exhibit higher density and Young's modulus (>5 GPa), higher yield strength (>150 MPa in compression), and high char yield. Di-functional benzoxazine monomers were synthesized by reacting DFDA with natural phenolic compounds and formaldehyde, resulting in solid powders that melt at temperatures between 70°C and 150°C. The resulting polybenzoxazine systems possess glass transition temperatures ranging from 220°C to 280°C and char yield as high as 65% measured at 1000°C by TGA in an inert environment. Despite the favorable properties of DFDA-based benzoxazines, improvements in process viscosity are required, mainly to obtain benzoxazine monomer systems that are liquid at room temperature and have low viscosity (<1 Pa*s) below 100°C. Approaches to address this challenge will be discussed. Furthermore, the impact of the furan ring on the curing reactions and resulting thermoset properties will be addressed as a common theme in all furan-based systems. Understanding these reaction pathways provides new ways of tuning material properties for composite, coating, and adhesive applications.