Microwave-Assisted Hydrothermal Decomposition of Super Absorbent Polymers

Ching, Teck Wei; Zhang, Jing; Collias, Dimitris I.; McDaniel, John; Simonyan, A. V.; Tanksale, Akshat; Holl, Mark M. Banaszak

doi:10.1021/acssuschemeng.0c04916

Cited by 10 publications

(6 citation statements)

References 44 publications

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“…Ultra-low molecular weight (ULMW) polymer has attracted great attention in the field of coatings, ink printing, adhesives, lubricants and additives et al, owing to the merits of low viscosity, good solubility, high transparency and excellent compatibility. [1] Traditionally, ULMW polymer is synthesized through the macromolecular degradation approach triggered by heat, light, electricity, ultrasound, shear and chemolysis et al [2] However, this method suffers from batch instability and downgrading of polymer quality. Through optimization of polymerization processes such as suspension, emulsion, dispersion, and precipitation, ULMW polymer can also be obtained.…”

Section: Introductionmentioning

confidence: 99%

A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight

Kuang

Zhang

et al. 2023

Angew Chem Int Ed

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Ultra‐low molecular weight (ULMW) CO2‐polyols with well‐defined hydroxyl end groups represent useful soft segments for the preparation of high‐performance polyurethane foams. However, owing to the poor proton tolerance of catalysts towards CO2/epoxide telomerization, it remains challenging to synthesize ULMW yet colorless CO2‐polyols. Herein, we propose an immobilization strategy of constructing supported catalysts by chemical anchoring of aluminum porphyrin on Merrifield resin. The resulting supported catalyst displays both extremely high proton tolerance (≈8000 times the equivalents of metal centers) and independence of cocatalyst, affording CO2‐polyols with ULMW (580 g mol−1) and high polymer selectivity (>99 %). Moreover, the ULMW CO2‐polyols with various architectures (tri‐, quadra‐, and hexa‐arm) can be obtained, suggesting the wide proton universality of supported catalysts. Notably, benefiting from the heterogeneous nature of the supported catalyst, colorless products can be facilely achieved by simple filtration. The present strategy provides a platform for the synthesis of colorless ULMW polyols derived from not only CO2/epoxides, but also lactone, anhydrides etc. or their combinations.

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Section: Introductionmentioning

confidence: 99%

A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight

Kuang

Zhang

et al. 2023

Angew Chem Int Ed

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“…Most of the discarded diapers and hygiene products containing net -NaPA are landfilled or incinerated, resulting in the waste of resources and the pollution of the natural environment with microplastics. , In recent years, society, politics, and researchers turned their attention to difficult-to-recycle polymers. For example, superabsorbers have been used for moisturizing soil, water desalination, and osmotic engines. − …”

Section: Introductionmentioning

confidence: 99%

Diapers to Thickeners and Pressure-Sensitive Adhesives: Recycling of Superabsorbers via UV Degradation

Li,

Scheiger,

Wang

et al. 2023

ACS Appl. Mater. Interfaces

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Superabsorbers based on crosslinked sodium polyacrylate polymers cannot be easily recycled, resulting in 2 million tons of superabsorbers being landfilled or burned every year. A fast and efficient strategy to recycle superabsorbers would significantly alleviate environmental pollution and promote a sustainable use of these polymers. Herein, the rapid recycling of crosslinked sodium polyacrylate hydrogels based on their inherent UV degradation is demonstrated without the need for chemicals besides water. A quantitative conversion of crosslinked sodium polyacrylate into soluble sodium polyacrylate is achieved in minutes, almost 200 times faster than a previous approach based on de-esterification. The obtained soluble sodium polyacrylate can be used, for example, as a thickener for aqueous dyes or can be esterified with n-butanol or 2-ethylhexanol to serve as a pressure-sensitive adhesive. The UV photodegradation and esterification of superabsorbers is fast, scalable, safe, and economical and yields polymers with controllable molecular weight in the range of 100−400 kg/mol. It thus offers distinct advantages over the chemical de-crosslinking strategies presented previously.

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“…For example, upon heating, polyacrylic acid is known to undergo dehydration and decarboxylation in bulk 17 and solution 18 , respectively. Recent efforts to sidestep this degradation using microwaves and added radical initiators led to oligomeric products with 50–60% decarboxylation 19 . While catalytic depolymerization methods 20 can, in principle, proceed without side-chain degradation, they have not yet been demonstrated for commercial sources of polyacrylic acid.…”

Section: Introductionmentioning

confidence: 99%

Giving superabsorbent polymers a second life as pressure-sensitive adhesives

et al. 2021

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An estimated 6.3 billion metric tons of post-consumer polymer waste has been produced, with the majority (79%) in landfills or the environment. Recycling methods that utilize these waste polymers could attenuate their environmental impact. For many polymers, recycling via mechanical processes is not feasible and these materials are destined for landfills or incineration. One salient example is the superabsorbent material used in diapers and feminine hygiene products, which contain crosslinked sodium polyacrylates. Here we report an open-loop recycling method for these materials that involves (i) decrosslinking via hydrolysis, (ii) an optional chain-shortening via sonication, and (iii) functionalizing via Fischer esterification. The resulting materials exhibit low-to-medium storage and loss moduli, and as such, are applicable as general-purpose adhesives. A life cycle assessment demonstrates that the adhesives synthesized via this approach outcompete the same materials derived from petroleum feedstocks on nearly every metric, including carbon dioxide emissions and cumulative energy demand.

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Microwave-Assisted Hydrothermal Decomposition of Super Absorbent Polymers

Cited by 10 publications

References 44 publications

A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight

A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight

Diapers to Thickeners and Pressure-Sensitive Adhesives: Recycling of Superabsorbers via UV Degradation

Giving superabsorbent polymers a second life as pressure-sensitive adhesives

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Microwave-Assisted Hydrothermal Decomposition of Super Absorbent Polymers

Cited by 10 publications

References 44 publications

A Supported Catalyst that Enables the Synthesis of Colorless CO2‐Polyols with Ultra‐Low Molecular Weight

A Supported Catalyst that Enables the Synthesis of Colorless CO2‐Polyols with Ultra‐Low Molecular Weight

Diapers to Thickeners and Pressure-Sensitive Adhesives: Recycling of Superabsorbers via UV Degradation

Giving superabsorbent polymers a second life as pressure-sensitive adhesives

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Product

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A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight

A Supported Catalyst that Enables the Synthesis of Colorless CO₂‐Polyols with Ultra‐Low Molecular Weight