Properties of Dilute Solutions of Polyurethanes. II. Branched Polymers

Satō, Hiroshi

doi:10.1246/bcsj.39.2340

Cited by 5 publications

(2 citation statements)

References 14 publications

(2 reference statements)

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“…Correspondingly, the peak D h values initially decrease from ∼4 nm at t = 5 min to ∼3 nm at t = 8 min and then remain nearly unchanged at t = 13 min. It is well established in the literature that a smaller D h value corresponds to a lower molecular weight. ,− For example, size exclusion chromatography (SEC) estimates a number average molecular weight ( M n ) of ∼27 kg mol –1 for the decross-linked PU extrudate obtained after reacting for 8 min (see Supporting Information for more SEC details). It is important to note that SEC characterizations might be convoluted by the complications from decross-linked PU extrudates’ branched architectures and intramolecular hydrogen bonding interactions. ,, Collectively, DLS and SEC indicate that the decross-linked PU extrudate’s molecular weight and its distribution (i.e., width of the D h distribution or breadth of the SEC elution peak) continue to evolve until t ≈ 8 min, at which the catalyzed carbamate exchange reactions in this system likely have reached an equilibrium state.…”

Section: Resultsmentioning

confidence: 99%

“…It is important to note that SEC characterizations might be convoluted by the complications from decross-linked PU extrudates' branched architectures and intramolecular hydrogen bonding interactions. 51,59,60 Collectively, DLS and SEC indicate that the decross-linked PU extrudate's molecular weight and its distribution (i.e., width of the D h distribution or breadth of the SEC elution peak) continue to evolve until t ≈ 8 min, at which the catalyzed carbamate exchange reactions in this system likely have reached an equilibrium state.…”

Section: Model Pu Network Deconstruction Via Small-molecule Carbamate...mentioning

confidence: 98%

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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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Section: Resultsmentioning

confidence: 99%

Section: Model Pu Network Deconstruction Via Small-molecule Carbamate...mentioning

confidence: 98%

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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Sedimentation Coefficients, Diffusion Coefficients, Partial Specific Volumes, Frictional Ratios, and Second Virial Coefficients of Polymers in Solution

Lechner

Nordmeier

Steinmeier

1999

The Wiley Database of Polymer Properties

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Thermoplastic urethane elastomers. VI. Dilute solution properties in various solvents

Seefried¹,

Koleske²,

Critchfield³

et al. 1980

J. Polym. Sci. Polym. Phys. Ed.

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A thermoplastic urethane elastomer prepared from a polycaprolactone diol, 4,4′‐diphenylmethane diisocyanate, and 1,5‐pentanediol was fractionated and the solution properties of the fractions were characterized in terms of viscosity and sedimentation. Mark‐Houwink relations were established for data obtained at 30° in various solvents: In dimethylacetamide, tetramethylurea, and N‐methyl pyrrolidone, the value of Kθ increased systematically in the range (1.7 to 2.0) × 10−3. Lower values of Kθ were obtained in dimethylformamide (0.8 × 10−3) and meta‐cresol (0.9 × 10−3). The molecular expansion coefficients in the various solvents were approximated from the experimental viscosity data. Short‐range interactions between the solvent molecules and polymer chains are suggested as possible causes for differences in the hydrodynamic parameters.

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Properties of Dilute Solutions of Polyurethanes. II. Branched Polymers

Cited by 5 publications

References 14 publications

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

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

Sedimentation Coefficients, Diffusion Coefficients, Partial Specific Volumes, Frictional Ratios, and Second Virial Coefficients of Polymers in Solution

Thermoplastic urethane elastomers. VI. Dilute solution properties in various solvents

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