Sustainable polyurethanes: toward new cutting-edge opportunities

Delavarde, Aliénor; Savin, Gaelle; Derkenne, Paul; Boursier, Marine; Morales-Cerrada, Roberto; Nottelet, Benjamin; Pinaud, Julien; Caillol, Sylvain

doi:10.1016/j.progpolymsci.2024.101805

Cited by 8 publications

(2 citation statements)

References 244 publications

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“…Thermoset polyurethanes are widely applied in electrical and electronic, aerospace, and medical fields owing to their excellent mechanical properties, aging resistance, and adhesive performance. , Generally, thermoset materials are characterized by a stable cross-linked network structure, which limits their reprocessability and recyclability. These shortcomings make their recovery difficult through melt processing or degradation after damage, resulting in a great waste. , The development of recyclable thermosetting polyurethane materials has attracted considerable attention from researchers in recent years. , …”

Section: Introductionmentioning

confidence: 99%

Multimethod Recyclable Thermoset Polybutadiene Polyurethane–Urea via Reversible Disulfide Bonds

Xu,

Fan,

Tao

et al. 2024

ACS Appl. Polym. Mater.

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The thermoset polyurethane materials are characterized by excellent comprehensive properties. However, the stable cross-linked network structure limits their reprocessability and recyclability. In this study, a thermoset polybutadiene polyurethane–urea material with excellent recyclable and reprocessable properties was prepared. The polyurethane–urea material was prepared by reacting isocyanate-capped polybutadiene prepolymer with curing agent 2,2′-dithiodianiline (DTDA containing dynamic disulfide bonds). The tensile strength and elongation at break of the materials were approximately 21.3 MPa and 604%, respectively. The thermoset pieces underwent a dynamic disulfide exchange reaction in DTDA/toluene solution and rapidly degraded to soluble fragments (a series of aniline-terminated low-molecular-weight materials) after 40 min at 60 °C. When the recycled soluble fragments were reacted with isocyanate compounds, a thermoset material was obtained again. The tensile strength and elongation at break of the material exceeded 98% of the initial values. After the above degradation–recycling process was repeated once more, the mechanical properties of the second recycled material remained unchanged. Additionally, the thermoset pieces were remolded after being hot-pressed at 150 °C for 10 min to produce high-performance materials. This study uses dynamic disulfide bonds to achieve degradation, recovery, and reprocessing utilization of a high-strength thermoset polyurethane–urea material.

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Section: Introductionmentioning

confidence: 99%

Multimethod Recyclable Thermoset Polybutadiene Polyurethane–Urea via Reversible Disulfide Bonds

Xu,

Fan,

Tao

et al. 2024

ACS Appl. Polym. Mater.

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“…Polyurethanes (PUs) are the sixth-largest manufactured consumer plastics, with a global market volume of ∼56 billion pounds (∼$87 billion market value) in 2023 and it expected to reach ∼69 billion pounds (∼$120 billion market value) by 2030. , Due to their tunable material properties, PUs are widely used in applications ranging from CASE industriescoatings, adhesives, sealants, and elastomersto PU foams (PUFs) for comfort and construction, where PUs are commonly synthesized as cross-linked thermosets. − Their permanent network structures prohibit recycling via conventional melt processing techniques used to recycle thermoplastics, leading to a low end-of-life PU recycling rate of only 5.5%. , A current PU recycling approach is the mechanical repurposing of cross-linked PUs toward low-end applications, e.g., PUFs are ground and combined with binders to produce carpet underlayers. , Another approach is chemical recycling such as glycolysis, which typically employs solvents, heat, and long reaction times to break carbamate linkages (i.e., urethane bonds) and depolymerize PUs into oligomers, followed by energy-intensive multistep separation processes to recover PU precursors (i.e., polyols). ,− Both of these two common methods have their own limitations, , which motivate the development of more circular and efficient PU recycling strategies.…”

Section: Introductionmentioning

confidence: 99%

Functional Upcycling of Polyurethane Thermosets into Value-Added Thermoplastics via Small-Molecule Carbamate-Assisted Decross-Linking Extrusion

Nettles,

Alfarhan,

Pascoe

et al. 2024

JACS Au

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The cross-linked structures of most commodity polyurethanes (PUs) hinder their recycling by common mechanical/chemical approaches. Catalyzed dynamic carbamate exchange emerges as a promising PU recycling strategy, which converts traditional static PU thermosets into reprocessable covalent adaptable networks (CANs). However, this approach has been limited to thermoset-to-thermoset reprocessing of PU CANs, accompanied by their well-preserved network structures and extremely high viscosities, which pose challenges to processing and certain applications. This study reports a catalytic decrosslinking extrusion process aided by small-molecule carbamates, which can upcycle PU thermosets into easily processable and functional PU thermoplastics in a solvent-free and high-throughput manner. Key to this process is the employment of small-molecule carbamates as decross-linkers to simultaneously deconstruct crosslinked PUs and functionalize the decross-linked PU chains, through catalyzed carbamate exchange reactions in a twin-screw extruder. This strategy applies to both aromatic and aliphatic cross-linked PU films and foams, and the amount of small-molecule carbamates required to decross-link PU networks is determined through thermal, chemical, and structural analyses of the resulting extrudates. This approach is generalizable to small-molecule carbamates with various steric/electronic structures and chemical functionalities including methacrylate, anthracene, and stilbene groups. The chain-end functionalization is confirmed by analyzing the purified decross-linked extrudates after dialysis. This thermoset-to-thermoplastic extrusion process represents a powerful approach for upcycling postconsumer PU thermosets into a library of thermoplastic PUs with controlled molecular weights and chain-end functionalities for diverse applications, including adhesives, photoresins, and stimuli-responsive materials, as demonstrated herein. In the future, this strategy could be extended to upcycle many other step-growth networks capable of undergoing catalytic bond exchange reactions, such as cross-linked polyureas and polyesters, contributing to plastic waste management in general.

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Synthesis of High Mechanical Strength and Thermally Recyclable and Reversible Polyurethane Adhesive by Diels–Alder Reaction

Xi,

Wang

2024

Macro Chemistry & Physics

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Recyclability of polyurethane materials is significant to relieve environmental problems caused by damaged polymers. Inspired by plenty of self‐healing properties based on dynamic covalent bonds. A high mechanical strength and thermally reversible polyurethane adhesive are acquired through co‐polymerization of poly‐1,4‐butylene adipate glycol (PBA), soybean oil‐based polyol (MESO), and toluene diisocyanate (TDI) whose linear polymer chains are constructed by Diels–Alder reaction between furfuryl alcohol (FA) and bismaleimide (BMI), named DAPU. Further, the obtained polyurethane adhesives show great recyclability, mechanical performance (Whose tensile strength can reach 91.7 MPa), and appropriate self‐healing ability through the thermally reversible Diels–Alder covalent bonds and hydrogen bonds between urethane groups, which may pave a way for further development of recyclable materials.

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Sustainable polyurethanes: toward new cutting-edge opportunities

Cited by 8 publications

References 244 publications

Multimethod Recyclable Thermoset Polybutadiene Polyurethane–Urea via Reversible Disulfide Bonds

Multimethod Recyclable Thermoset Polybutadiene Polyurethane–Urea via Reversible Disulfide Bonds

Functional Upcycling of Polyurethane Thermosets into Value-Added Thermoplastics via Small-Molecule Carbamate-Assisted Decross-Linking Extrusion

Synthesis of High Mechanical Strength and Thermally Recyclable and Reversible Polyurethane Adhesive by Diels–Alder Reaction

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