Advances in the degradation and recycling of polyurethanes: biodegradation strategies, MALDI applications, and environmental implications

Polyurethanes pose significant environmental challenges due to their limited recyclability and slow biodegradation. This review highlights recent advancements in polyurethanes degradation and recycling, with a particular focus on the application of Matrix-Assisted Laser Desorption/Ionization techniques. This methods have made significant progress in analyzing environmental contamination by polyurethanes, offering a detailed understanding of degradation products and polymer structures. The review discusses key advancements in biostimulation and bioaugmentation strategies that have led to notable improvements in polyurethanes degradation rates in soils, offering potential solutions for large-scale waste management. Additionally, the comparative advantages of recycling methods, such as glycolysis, aminolysis, and hydrolysis, are highlighted, focusing on their efficiency, environmental impact, and potential for industrial application. The scalability of these technologies is also considered, with potential for broad implementation in the recycling industry. Furthermore, Matrix-Assisted Laser Desorption/Ionization techniques are examined as a powerful tool for analyzing polyurethanes-based waste, with insights into optimizing sample preparation and improving detection sensitivity for large-scale applications. This review provides a comprehensive overview of current and emerging trends in polyurethanes degradation and recycling, emphasizing their industrial relevance and future prospects.

Polyethylene Glycol-Isophorone Diisocyanate Polyurethane Prepolymers Tailored Using MALDI MS

The reaction of diols with isocyanates, leading to mono-functional and di-functional prepolymers may be investigated using various characterization methods which show the overall conversion of isocyanate monomers. On the other hand, matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) polymer characterization can be employed to identify the monomer units, the end-group functionalities, molecular weight averages, and to determine the copolymer sequence. Herein, we focus on prepolymer synthesis using isophorone diisocyanate (IPDI), a widely used diisocyanate for prepolymers preparation, especially in waterborne polyurethane materials. Thus, the reaction between polyethylene glycol diol and IPDI was in-depth investigated by mass spectrometry to determine the influence of the reaction parameters on the prepolymer's structure. The relative content of the different functional oligomer species at given reaction times was determined in the reaction mixture. More specifically, the offline analysis revealed the influence of reaction parameters such as reaction temperature, the concentration of reactants, and the amount of dibutyltin dilaurate catalyst. The established MALDI MS analysis involved measurements of samples, first, directly collected from the reaction mixture and secondly, following derivatization with methanol. The obtained results revealed the effects of reaction parameters on the functionalization reaction with isocyanates, allowing to achieve a better reaction control.

Mass Spectrometry of Polyurethanes

This review covers the applications of mass spectrometry (MS) and its hyphenated techniques to characterize polyurethane (PU) synthetic polymers and their respective hard and soft segments. PUs are commonly composed of hard segments including methylene bisphenyl diisocyanate (MDI) and toluene diisocyanate (TDI), and soft segments including polyester and polyether polyols. This literature review highlights MS techniques such as electrospray ionization (ESI), matrix assisted laser/desorption ionization (MALDI), ion mobility-mass spectrometry (IM-MS), and computational methods that have been used for the characterization of this polymer system. Here we review specific case studies where MS techniques have elucidated unique features pertaining to the makeup and structural integrity of complex PU materials and PU precursors.