Towards high-performance polyurethanes: a mechanism of amine catalyzed aromatic imide formation from the reaction of isocyanates with anhydrides

Guo, Yunfei; Spicher, Sebastian; Cristadoro, Anna; Deglmann, Peter; Sijbesma, Rint P.; Tomović, Željko

doi:10.1039/d3py00109a

Cited by 3 publications

(3 citation statements)

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“…Generally, the rate of the reaction between isocyanates and anhydrides can be increased with urea, which forms during the reaction between NCO and NH groups 35 . In this study, we used NMA as a precatalyst to facilitate the formation of a urea group (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Casting poly(urethane‐imide) elastomers with improved thermoviscoelasticity

Lin,

Lou,

Cheng

et al. 2023

J of Applied Polymer Sci

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Polyurethane (PU) is a versatile material that can be customized to meet specific commercial requirements in different industries because of its favorable mechanical properties. However, it is not resistant to high temperatures, and it requires structural modifications before it can be used in high‐temperature structural materials. In this study, isocyanates and anhydrides are copolymerized at high temperatures to obtain a solvent‐free oligomer, thus eliminating the risks associated with highly polar aprotic solvents. A casting technique is used to synthesize a solid poly(urethane‐imide) (PUI) elastomer. According to the results, casting PUI (CPUI) exhibits optimal physical properties at a hard segment content of 30.5%. Incorporating an ether, symmetric, or imide structure into CPUI may reduce its hysteresis and improve its thermal creep performance. Compared with PU, CPUI exhibits considerably higher creep aging resistance. In dynamic load application tests, CPUI wheels take a substantially longer time to reach failure compared with PU wheels. Overall, CPUI is an environmentally friendly material with high elasticity, low creep, and high heat aging resistance and is suitable for static and dynamic manufacturing applications.

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Section: Resultsmentioning

confidence: 99%

Casting poly(urethane‐imide) elastomers with improved thermoviscoelasticity

Lin,

Lou,

Cheng

et al. 2023

J of Applied Polymer Sci

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“…Recently, we have discovered that it is possible to perform the reaction of aromatic isocyanates and anhydrides in solvent-free conditions with high conversion. The use of secondary amine as a pre-catalyst and tertiary amine as a cocatalyst compensates the lack of catalytic effect from strong polar solvents and accelerates the reaction speed . We also discovered that during the imide formation from aromatic isocyanate and anhydride with secondary amine as a pre-catalyst, the urea that forms from the reaction of aromatic isocyanate and secondary amine is the actual active catalyst.…”

Section: Introductionmentioning

confidence: 93%

“…The use of secondary amine as a pre-catalyst and tertiary amine as a cocatalyst compensates the lack of catalytic effect from strong polar solvents and accelerates the reaction speed. 45 We also discovered that during the imide formation from aromatic isocyanate and anhydride with secondary amine as a precatalyst, the urea that forms from the reaction of aromatic isocyanate and secondary amine is the actual active catalyst. With the help of a tertiary amine as a cocatalyst, the deprotonated urea opens the ring of an anhydride to form an amic acid intermediate.…”

Section: Introductionmentioning

confidence: 99%

Solvent-Free Preparation of Thermally Stable Poly(urethane-imide) Elastomers

Guo

Cristadoro²,

Kleemann³

et al. 2023

ACS Appl. Polym. Mater.

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Polyurethanes (PUs) are widely used in many applications due to their versatile chemical and physical properties. To meet the increasing demands on PU with respect to intrinsic mechanical and thermal properties, they can be modified with thermally stable aromatic imide structures to form poly(urethane imide) (PUI). However, the preparation of PUI materials has been limited by the need for strong polar solvents, which hinder their industrial scale development. In this work, we prepared imide-containing isocyanate-terminated prepolymers via the reaction of polymeric aromatic or aliphatic isocyanates and pyromellitic dianhydride in completely solvent-free conditions. The subsequent PUI elastomers made from these prepolymers exhibited enhanced char formation and stiffness in comparison to the reference elastomers without imide structures, among which the aromatic PUI elastomer shows improved flame retardancy according to the initial cone calorimetry measurement. This work demonstrates the potential use of imide prepolymers in other PU applications where high thermal stability and flame retardancy are required. The solvent-free synthesis also paves a way for the large-scale production of PUI materials.

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