{"title":"Cross-Linking Agent Based on the Dynamic Bond and Resultant Epoxy Adhesive with a High Mechanical Property","authors":"Yaxin Chen, Qinghui Jin, Feng Chen, Qiang Zheng* and Yonggang Shangguan*, ","doi":"10.1021/acsapm.4c0239810.1021/acsapm.4c02398","DOIUrl":null,"url":null,"abstract":"<p >Due to the high cross-linking density of cured epoxy resins resulting in the inherent brittleness of adhesives, epoxy adhesives are less resistant to crack initiation and growth and often fail in a brittle manner. Thus, promoting maximum elongation and ductility without sacrificing mechanical strength remains challenging. In this study, according to molecular structure design, through using amide bonds to combine flexible aliphatic amines and furan structures by a simple transesterification method, a polyamide curing agent, <i>N</i>,<i>N</i>-bis(6-aminohexyl)furan-2,5-dicarboxamide oligomer (FDAH), was obtained. This curing agent was used to prepare a series of high-performance epoxy adhesives based on noncovalent interactions. Noncovalent bond interactions could provide additional aid in energy dissipation and dynamic behavior, while flexible aliphatic chains ensure enough flexibility in the network. On the one hand, the adhesion strength of the adhesive was improved by introducing noncovalent interactions into and between molecular chains. On the other hand, the structure of furan-amide and the characteristics of flexible aliphatic amines were combined to adjust the cross-linking density of structural adhesives, thereby improving their mechanical properties. By adjusting the content of the modified curing agent in the epoxy network, the molecular structure, curing behavior, and properties of the cured epoxy adhesive were systematically characterized, and it was found that the prepared adhesive had high tensile strength (62.4 MPa), large elongation at break (14%), excellent adhesion performance, suitable sizing, and curing window. The strengthening mechanism of reversible dynamic bonds on adhesives was also preliminarily elucidated. Overall, this work provides more possibilities for tuning the physical properties of cross-linked networks, and using similar strategies to enhance rigid polymers can achieve a good combination of high strength and scalability.</p>","PeriodicalId":7,"journal":{"name":"ACS Applied Polymer Materials","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Applied Polymer Materials","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acsapm.4c02398","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Due to the high cross-linking density of cured epoxy resins resulting in the inherent brittleness of adhesives, epoxy adhesives are less resistant to crack initiation and growth and often fail in a brittle manner. Thus, promoting maximum elongation and ductility without sacrificing mechanical strength remains challenging. In this study, according to molecular structure design, through using amide bonds to combine flexible aliphatic amines and furan structures by a simple transesterification method, a polyamide curing agent, N,N-bis(6-aminohexyl)furan-2,5-dicarboxamide oligomer (FDAH), was obtained. This curing agent was used to prepare a series of high-performance epoxy adhesives based on noncovalent interactions. Noncovalent bond interactions could provide additional aid in energy dissipation and dynamic behavior, while flexible aliphatic chains ensure enough flexibility in the network. On the one hand, the adhesion strength of the adhesive was improved by introducing noncovalent interactions into and between molecular chains. On the other hand, the structure of furan-amide and the characteristics of flexible aliphatic amines were combined to adjust the cross-linking density of structural adhesives, thereby improving their mechanical properties. By adjusting the content of the modified curing agent in the epoxy network, the molecular structure, curing behavior, and properties of the cured epoxy adhesive were systematically characterized, and it was found that the prepared adhesive had high tensile strength (62.4 MPa), large elongation at break (14%), excellent adhesion performance, suitable sizing, and curing window. The strengthening mechanism of reversible dynamic bonds on adhesives was also preliminarily elucidated. Overall, this work provides more possibilities for tuning the physical properties of cross-linked networks, and using similar strategies to enhance rigid polymers can achieve a good combination of high strength and scalability.
期刊介绍：
ACS Applied Polymer Materials is an interdisciplinary journal publishing original research covering all aspects of engineering, chemistry, physics, and biology relevant to applications of polymers.
The journal is devoted to reports of new and original experimental and theoretical research of an applied nature that integrates fundamental knowledge in the areas of materials, engineering, physics, bioscience, polymer science and chemistry into important polymer applications. The journal is specifically interested in work that addresses relationships among structure, processing, morphology, chemistry, properties, and function as well as work that provide insights into mechanisms critical to the performance of the polymer for applications.
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