Catalyst-free curing and closed-loop recycling of carboxylated functionalized rubber by a green crosslinking strategy

Feng, Haoran; Tian, Chenru; Zhang, Ganggang; Zhang, Liqun

doi:10.1016/j.polymer.2021.124237

Cited by 14 publications

(9 citation statements)

References 32 publications

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“…However, most of the compounds used to induce secondary reactions or to form free radicals, as well as common reagents for some click reactions are presumably toxic and negatively affect biological properties and induce cytotoxicity issues [ 223 ]. Therefore, the main challenge of these procedures would be to move towards the implementation of the abovementioned green alternative compounds to induce complementary group reactions or free radical initiators that do not harm the biological properties of the resulting systems [ 224 , 225 ]. In addition, further research to obtain specific enzymes would be another interesting approach to attain chemically cross-linked structures avoiding the use of toxic compounds [ 226 , 227 ].…”

Section: Synthesis Of Hydrogelsmentioning

confidence: 99%

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

et al. 2022

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Nowadays, there are still numerous challenges for well-known biomedical applications, such as tissue engineering (TE), wound healing and controlled drug delivery, which must be faced and solved. Hydrogels have been proposed as excellent candidates for these applications, as they have promising properties for the mentioned applications, including biocompatibility, biodegradability, great absorption capacity and tunable mechanical properties. However, depending on the material or the manufacturing method, the resulting hydrogel may not be up to the specific task for which it is designed, thus there are different approaches proposed to enhance hydrogel performance for the requirements of the application in question. The main purpose of this review article was to summarize the most recent trends of hydrogel technology, going through the most used polymeric materials and the most popular hydrogel synthesis methods in recent years, including different strategies of enhancing hydrogels’ properties, such as cross-linking and the manufacture of composite hydrogels. In addition, the secondary objective of this review was to briefly discuss other novel applications of hydrogels that have been proposed in the past few years which have drawn a lot of attention.

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Section: Synthesis Of Hydrogelsmentioning

confidence: 99%

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

et al. 2022

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“…In our previous work, it was found that the XNBR could be cross-linked by epoxy resin, such as biobased ESO and commercial TGDDM. Moreover, the end-of-life elastomer materials could achieve closed-loop recycling by the selective ester bond cleavage. , Hence, the lignin/XNBR composites could also be chemically cross-linked and construct a covalent interface between the XNBR matrix and lignin due to the reaction of the epoxy group with the carboxyl group and phenolic hydroxyl group. The introduction of the chemical cross-linking network could further improve the mechanical performances and heat resistance of the lignin/XNBR composites.…”

Section: Resultsmentioning

confidence: 99%

Mechanically Robust, Self-Repairable, Shape Memory and Recyclable Ionomeric Elastomer Composites with Renewable Lignin via Interfacial Metal–Ligand Interactions

Zhang

Tian

Shi

et al. 2022

ACS Appl. Mater. Interfaces

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Lignin, the most abundant aromatic polymer in nature, is one of the most promising renewable feedstocks for value-added polymer products. However, it is challenging to prepare high-performance and multifunctional polymer materials with renewable lignin because of its poor compatibility with the elastomer matrix. In fact, lignin often requires solvent fractionation, chemical modification, or prohibitively expensive additives. This work develops a cost-effective strategy to prepare ionomeric elastomer composites based on a commercial carboxyl elastomer and a high content of lignin without purification or chemical modification. The compatibility between the elastomer and lignin is improved by the incorporation of zinc oxide which creates metal−ligand coordination at the interfaces between the carboxyl groups of the elastomer and the oxygen-bearing groups of the lignin. This results in fine dispersion of the lignin in the elastomer matrix, even when its content reaches 50 wt %. The lignin/elastomer composites show excellent mechanical properties, which are attributed to the reinforcing effect of the lignin domains and the presence of abundant sacrificial coordination bonds. Moreover, ionic bonds and ionic aggregates created by the neutralization of the zinc ions with the carboxyl groups of the elastomer behave as physical crosslinks which endow the composites with excellent recyclability; namely, their mechanical properties are retained or even improved after multiple reprocessing cycles. They also show good self-repairability and shape memory. Hence, this work may open up new avenues to utilize lignin as a renewable alternative to petroleum derivatives for designing and fabricating high-performance and multifunctional elastomer materials.

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“…In the past decade, some novel cross-linking strategies for rubbers have been established. The basic philosophy is to construct the new cross-linking network structures based on functionalized rubbers as matrixes and new organic molecules rather than sulfur or peroxide as cross-linking agents. ,, Norvez et al − demonstrated that dodecanedioic acid (DDA) could effectively cross-link ENR and form the ester linkages in cross-linked networks based on the addition reaction between epoxide groups onto ENR chains and carboxyl groups in DDA molecules. The epoxide groups onto the ENR backbone showed insufficient reactivity with the carboxyl groups; thus, the cross-linking reaction of ENR with DDA should be catalyzed by toxic and odorous 1,2-dimethylimidazole (DMI).…”

Section: Introductionmentioning

confidence: 99%

Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

Song

Wang

Xing

et al. 2023

ACS Sustainable Chem. Eng.

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The bio-based epoxidized natural rubber (ENR) is considered a promising platform to design and fabricate sustainable and high-performance rubber materials. The epoxide sites in the ENR chains contribute to designing a green cross-linking strategy to reduce the release of toxic volatile organic compounds and achieve the recycling of end-of-life rubbers. However, it is still challenging to achieve a catalyst-free and effective cross-linking strategy and obtain a cross-linked ENR with mechanically robust properties. Herein, a series of carboxylic acids with different chain lengths and degrees of functionality were synthesized through the catalyst-free and solvent-free alcoholysis of maleic anhydride and served as cross-linkers for ENR. We demonstrated that the increased chain lengths and degrees of functionality of carboxylic acids were conducive to increasing the rate and efficiency of the epoxy–acid cross-linking reaction and improving the mechanical properties of ENR compared with those of commercial maleic acid. Hence, ENR could be facilely and effectively cross-linked by the modified carboxylic acids without additional additives, producing β-hydroxy ester linkages. The mechanical properties of ENR/carbon black composites could be facilely adjusted via changing the structure and content of the cross-linkers. Due to the introduction of the exchangeable β-hydroxy ester linkages, the covalently cross-linked networks could be able to achieve topological rearrangements via transesterifications, thus conferring the cross-linked ENR with good reprocessability. Moreover, the carboxylic acid-cured ENR showed the improved thermal-oxidative aging resistance compared to sulfur-curd one because the formed ester cross-links are thermally stable. This work provides a catalyst-free, efficient and green cross-linking strategy for the epoxidized elastomer, which could open a broad application scenario in vitrimer-like rubbers.

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Catalyst-free curing and closed-loop recycling of carboxylated functionalized rubber by a green crosslinking strategy

Cited by 14 publications

References 32 publications

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

Mechanically Robust, Self-Repairable, Shape Memory and Recyclable Ionomeric Elastomer Composites with Renewable Lignin via Interfacial Metal–Ligand Interactions

Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

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