CHEMICAL UPCYCLING TO MONOMERS (CUCMS) OF ESTER-BASED PLASTICS VIA AMINOLYSIS
Creators: name: Shao, Lin
Publisher: name: Washington State University
Year: 2026
Subjects: chemical upcycling
monomers
Ester-based Plastics
Aminolysis

description: In this research, a method of chemical upcycling to monomers (CUCMs) for ester-based plastics was demonstrated. Polylactic acid (PLA) with linear structure was decomposed into monomer, N-lactoyl ethanolamine (N-LEA), at mild conditions (100 °C, 1 h, at atmosphere) through aminolysis. N-LEA was further derivatized by reacting with methacrylic anhydride to yield a cross-linkable dimethacrylate monomer. When combined with a comonomer and initiator, this leads to the production of a photocurable resin. This resin is compatible with various commercially available photocuring 3D printers. The resulting 3D printed parts, derived from PLA waste materials, demonstrate impressive properties including a tensile strength of 58.6 MPa, a Young's modulus of 2.8 GPa, and a glass transition temperature of 180 °C.Additionally, one-pot synthesis was employed to produce high-performance photo-curable 3D printing resin. In this effort, an excess amount of methacrylic anhydride was purposely employed to react with N-LEA in the preparation of the dimethacrylate. The residual methacrylic anhydride and methacrylic acid formed in the reaction mixture acted as solvent for the dimethacrylate product. The resulting solution is a photocurable resin ready for 3D printing without any other treatment. The 3D printed parts display a set of unparalleled properties compared to some of the strongest photocurable 3D printing resin on the market. The tensile strength of 132.8 MPa, glass transition temperature of ~190 °C, and heat deflection temperature ~163 °C.
description: Furthermore, aminolysis kinetics of polylactic acid (PLA) in 2-aminoethanol (EA) under normal atmospheric pressure was investigated, utilizing a gravimetric analysis method. Results indicated that diffusion had minimal impact on the overall degradation process and could be largely discounted. The surface area of PLA emerged as a critical factor influencing the kinetics of aminolysis. Various kinetic models, including first- and second-order equations, were employed to evaluate PLA’s aminolysis kinetics. Among these models, the first-order kinetic model demonstrated the most accurate depiction of PLA’s degradation behavior, with a high regression coefficient (R2 &gt; 0.98) observed within the temperature range of 60-90 °C. By applying the Arrhenius equation, the activation energy of the aminolysis reaction was determined to be 70.06 kJ/mol, with a pre-exponential factor of 2.058×107. This study not only highlights the importance of reaction conditions such as temperature and surface area in PLA aminolysis but also offers a quantitative insight into the reaction kinetics, facilitating optimization for industrial applications.
description: At last, anhydride cured diglycidyl ether of bisphenol epoxy that contains ester linkage in the crosslinked network structure can be also decomposed into monomers with 2-aminoethanol by aminolysis without using any catalyst. The epoxy resin underwent complete decomposition at 160°C within 4 hours, yielding two distinct high-purity monomers, namely amidodiol from the anhydride component (HHPA-OH) and bisphenol A epoxy component (BPA-OH). Subsequently, BPA-OH was employed in the synthesis of a polyurethane coating, exhibiting exceptional properties including a high glass transition temperature (88.9°C), scratch hardness (8H), gouge hardness (6H), adhesive strength (5B), and robust solvent resistance. HHPA-OH, possessing two hydroxyl groups, was further reacted with methacrylic anhydride to produce a dimethacrylate monomer. This monomer served as an effective crosslinker to produce photo-curable 3D printing thermosetting polymers, achieving impressive tensile strength of up to 64 MPa and impact strength of 4.86 kJ/m2. This upcycling method allows for a more efficient utilization of degradation products, upcycling ester-based plastics wastes into high-performance materials.