The objective of this study was to replace elastomer crosslinking based on chemical covalent bonds by reversible systems under processing. One way is based on ionic bonds creation, which allows a physical crosslinking while keeping the process reversibility. However, due to the weak elasticity recovery of such a physical network after a long period of compression, the combination of both physical and chemical networks was studied. In that frame, an ethylene-propylene-diene terpolymer grafted with maleic anhydride (EPDM-g-MA) was crosslinked with metal salts and/or dicumyl peroxide (DCP). Thus, the influence of these two types of crosslinking networks and their combination were studied in detail in terms of compression set. The second part of this work was focused on the influence of different metallic salts (KOH, ZnAc) and the sensitivity to the water of the physical crosslinking network. Finally, the combination of ionic and covalent network allowed combining the processability and better mechanical properties in terms of recovery elasticity. KAc proved to be the best ionic candidate to avoid water degradation of the ionic network and then to preserve the elasticity recovery properties under aging.
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http://dx.doi.org/10.3390/polym13183161 | DOI Listing |
ACS Mater Au
January 2025
Department of Electrical and Electronic Engineering, Kyushu Institute of Technology, 1-1 Sensuicho, Tobataku, Kitakyushu, Fukuoka 804-8550, Japan.
Ionic gels (IGs), ionic liquids (ILs) dispersed in polymers, exhibit extremely low vapor pressure, electrochemical and thermal stability, and excellent mechanical characteristics; therefore, they are used for fabricating stretchable sensors, electrochemical transistors, and energy storage devices. Although such characteristics are promising for flexible and stretchable electronics, the mechanical stress-induced ruptured covalent bonds forming polymer networks cannot recover owing to the irreversible interaction between the bonds. Physical cross-linking via noncovalent bonds enables the interaction of polymers and ILs to form supramolecular IGs (SIGs), which exhibit favorable characteristics for wearable devices that conventional IGs with noncovalent bonds cannot achieve.
View Article and Find Full Text PDFStem cells adapt to their local mechanical environment by rearranging their cytoskeleton, which underpins the evolution of their shape and fate as well as the emergence of tissue structure and function. Here, in the second part of a two-part experimental series, we aimed to elucidate spatiotemporal cytoskeletal remodeling and resulting changes in morphology and mechanical properties of cells and their nuclei. Akin to mechanical testing of the most basic living and adapting unit of life, i.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Department of Applied Science and Technology, Politecnico di Torino, Viale Teresa Michel 5, 15121 Alessandria, Italy.
In polymer science and technology, the distinction between thermoplastic and thermosetting materials has always been sharp, clear, and well-documented: indeed, the former can theoretically be reprocessed a potentially infinite number of times by heating, forming, and subsequent cooling. This cannot be done in the case of thermosetting polymers due to the presence of cross-links that covalently bind the macromolecular chains, giving rise to insoluble and infusible polymeric networks. In 2011, the discovery of vitrimers revolutionized the classification mentioned above, demonstrating the possibility of using new materials that consist of covalent adaptable networks (CANs): this way, they can change their topology through thermally-activated bond-exchange reactions.
View Article and Find Full Text PDFAdv Healthc Mater
January 2025
Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, College of Bioengineering, Chongqing, 400044, P. R. China.
Decellularized artificial blood vessels prepared using physical and chemical methods often exhibit limitations, including poor mechanical performance, susceptibility to inflammation and calcification, and reduced patency. Cross-linking techniques can enhance the stiffness, as well as anti-inflammatory and anti-calcification properties of decellularized vessels. However, conventional cross-linking methods fail to effectively alleviate residual stress post-decellularization, which significantly impacts the patency and vascular remodeling following the implantation of artificial vessels.
View Article and Find Full Text PDFInt J Biol Macromol
January 2025
Chemistry Department, Faculty of Science, Damietta University, Damietta 34517, Egypt. Electronic address:
The VCo-LDH/CS hydrogel beads were created by combining VCo-layered double hydroxide (VCo-LDH) and chitosan (CS) using a cross-linking process with epichlorohydrin. These beads were specifically designed to remove tetracycline (TTC). To characterize the VCo-LDH/CS hydrogel beads, several analytical techniques were used, with PXRD, XPS, FESEM, EDX, and FT-IR.
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