Hydrolysis of aromatic polyurethane in water under high pressure of CO<sub>2</sub>

Motokucho, Suguru; Yamaguchi, Akito; Nabetani, Yu; Morikawa, Hiroshi; Nakatani, Hisayuki

doi:10.1002/pola.28576

Cited by 27 publications

(46 citation statements)

References 14 publications

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“…These experimental data suggested that the WIR had the same repeating structure as H‐PU, and no side reaction occurred at the main chain upon hydrolysis. These results matched those of the hydrolysis of M‐PU, as previously reported …”

Section: Resultssupporting

confidence: 63%

“…First, 0.50 g of H‐PU and 20 mL of water were placed into a 200 mL stainless autoclave equipped with a pressure gauge followed by the introduction of an appropriate amount of liquid CO 2 . Then, the autoclave was heated using a band heater under a high pressure of CO 2 (8.0 MPa).…”

Section: Methodsmentioning

confidence: 99%

“…The degree of hydrolysis of PUs was estimated from the following equations:

W_{0} = Weight of starting PU

W_{WIR} = Weight ofWIR

Degree of hydrolysis true(% true) = [(W_{0} - W_{WIR}) / W_{0}] \times 100

…”

Section: Methodsmentioning

confidence: 99%

“…In this system, CO 2 produces carbonic acid in situ by reaction with water; then, the formed carbonic acid acts as an acid catalyst . Hydrolysis, reduction, and dehydration reactions in the presence of this catalytic system have been already reported.…”

Section: Introductionmentioning

confidence: 94%

“…Besides, this hydrolysis reaction produced the corresponding raw chemicals, diamine and diol, derived from the cleavage of the repeating units of M‐PU in excellent yields. A plausible reaction mechanism was discussed in a previous study, according to which the acid activated the carbonyl group and then the hydrolytic cleavage of the urethane group occurred. For this process to occur, it is important that this chemical recycling system should include only CO 2 and water, and the concentration of the aqueous solution in the hydrolyzed reaction mixture allows to easily afford the raw chemicals with no need of neutralization or extraction.…”

Section: Introductionmentioning

confidence: 99%

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Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system

Motokucho

Nabetani

Morikawa

et al. 2017

J of Applied Polymer Sci

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In order to develop a chemical recycling system of polyurethanes (PUs), environment‐friendly hydrolysis of two types of aliphatic PUs was studied under pressured CO2 in water, in which the carbonic acid generated from CO2 acted as an acid catalyst. Two PUs, namely H‐PU or I‐PU, were synthesized starting from 1,4‐butanediol and 1,6‐hexamethylene diisocyanate or isophorone diisocyanate, respectively. The hydrolysis of PUs depended on the experimental conditions, such as the temperature and CO2 pressure. As a result, 98% of H‐PU and 91% of I‐PU were successfully hydrolyzed under the typical conditions of 190 °C for 24 h at 8.0 MPa CO2. The reaction mixtures afforded 1,4‐butanediol and diamines without the formation of any byproducts. Both of these raw materials generated from the originated PUs by selective hydrolytic cleavage of the urethane linkages, and they were easily isolated in high yields simply by evaporation of the water‐soluble components within the reaction mixture. By comparing the results of the two aliphatic PUs with those of an aromatic PU (M‐PU), the hydrolyzability was found to decrease in the order H‐PU, I‐PU, and M‐PU. The difference can be ascribed to the hydrophilicity of the aliphatic or aromatic groups connected to the urethane moieties at the terminals of PUs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45897.

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Section: Resultssupporting

confidence: 63%

Section: Methodsmentioning

confidence: 99%

“…The degree of hydrolysis of PUs was estimated from the following equations:

W_{0} = Weight of starting PU

W_{WIR} = Weight ofWIR

Degree of hydrolysis true(% true) = [(W_{0} - W_{WIR}) / W_{0}] \times 100

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system

Motokucho

Nabetani

Morikawa

et al. 2017

J of Applied Polymer Sci

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Sustainable and Scalable Synthesis of Acetal‐Containing Polyols as a Platform for Circular Polyurethanes

Schara,

Cristadoro,

Sijbesma

et al. 2024

ChemSusChem

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Polyurethanes (PUs) are highly versatile polymers widely utilized across industries. However, chemical recycling of PU possess significant challenges due to the harsh conditions required, and the formation of complex mixtures of oligomers upon depolymerization. Addressing this inherent lack of recyclability, we developed closed‐loop recyclable PU materials by integrating cleavable acetal groups. We present a sustainable and scalable synthesis method for acetal‐containing polyols (APs) through aldehyde‐diol polycondensation, utilizing reusable heterogeneous catalysis. Three APs with different hydrolytic stabilities depending on the structure of acetal groups were synthesized from formaldehyde, acetaldehyde, and propionaldehyde with 1,6‐hexanediol (H16). These APs were employed alongside 4,4'‐methylene diisocyanate (MDI) for preparation of PU materials. The resulting PUs exhibited mechanical properties comparable to or surpassing those of conventional PUs, while demonstrating excellent recyclability under acidic conditions. Notably, hydrolysis of PU materials based on acetaldehyde‐derived APs yielded remarkable monomer recovery rates, with 89% for H16 and 84% for 4,4'‐methylenedianiline, a precursor to MDI. Furthermore, we successfully demonstrated closed‐loop recycling by synthesizing APs from recovered H16, resulting in PU materials with identical properties to the original PU. This achievement highlights the potential for establishing a closed‐loop recycling system for acetal‐containing PUs, contributing to the advancement of a sustainable and circular economy.

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Selectively Depolymerizable Polyurethanes from Unsaturated Polyols Cleavable by Olefin Metathesis

Jones

Staiger

Powers

et al. 2020

Macromol. Rapid Commun.

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This communication describes a novel series of linear and crosslinked polyurethanes (PUs) and their selective depolymerization under mild conditions. Two unique polyols are synthesized bearing unsaturated units in a configuration designed to favor ring‐closing metathesis (RCM) to five‐ and six‐membered cycloalkenes. These polyols are co‐polymerized with toluene diisocyanate to generate linear PUs and trifunctional hexamethylene‐ and diphenylmethane‐based isocyanates to generate crosslinked PUs. The polyol design is such that the RCM reaction cleaves the backbone of the polymer chain. Upon exposure to dilute solutions of Grubbs’ catalyst under ambient conditions, the PUs are rapidly depolymerized to low molecular weight, soluble products bearing vinyl and cycloalkene functionalities. These functionalities enable further re‐polymerization by traditional strategies for polymerization of double bonds. It is anticipated that this general approach can be expanded to develop a range of chemically recyclable condensation polymers that are readily depolymerized by orthogonal metathesis chemistry.

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Hydrolysis of aromatic polyurethane in water under high pressure of CO₂

Cited by 27 publications

References 14 publications

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system

Sustainable and Scalable Synthesis of Acetal‐Containing Polyols as a Platform for Circular Polyurethanes

Selectively Depolymerizable Polyurethanes from Unsaturated Polyols Cleavable by Olefin Metathesis

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Hydrolysis of aromatic polyurethane in water under high pressure of CO2

Cited by 27 publications

References 14 publications

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO2‐water system

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO2‐water system

Sustainable and Scalable Synthesis of Acetal‐Containing Polyols as a Platform for Circular Polyurethanes

Selectively Depolymerizable Polyurethanes from Unsaturated Polyols Cleavable by Olefin Metathesis

Contact Info

Product

Resources

About

Hydrolysis of aromatic polyurethane in water under high pressure of CO₂

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system

Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO₂‐water system