Healable, Recyclable, and High‐Stretchable Polydimethylsiloxane Elastomer Based on Synergistic Effects of Multiple Supramolecular Interactions

Abstract

Polydimethylsiloxane (PDMS) is one of the preferred materials for researchers to design smart flexible sensors or devices due to its excellent chain flexibility as well as the unique features of transparency, nontoxicity, and biocompatibility. To fulfill the requirement of the service safety and long‐term application, the development of healable PDMS‐based substrates is booming. However, it is still a big challenge to develop PDMS elastomers with good healing performance, high strength, high stretchability, and high toughness simultaneously. Herein, a healable, recyclable, and highly stretchable PDMS‐based elastomer is prepared by incorporating different supramolecular interactions including π–π stacking and hydrogen bonding into the matrix. This elastomer is fabricated via a one‐pot polycondensation reaction among bis(3‐aminopropyl)‐terminated PDMS , functional monomer pyrene diol and 1,6‐diisocyanatohexane. The mechanical properties and self‐healing properties can be easily tuned by varying the density of π–π stacking to hydrogen bonding. The resultant elastomer exhibits very high strength and high stretchability with a fracture strength of 7.46 MPa and fracture strain of 2174%, and it achieves nearly complete self‐healing (96%) at 110 °C for 1 h.

Extra-Soft Self-Healable Supramolecular Silicone Elastomers from Bis-Amide-PDMS Multiblock Copolymers Prepared by Aza-Michael Reaction

“…These are associated with transitions that occur in the PDMS matrix and in the bis-amide-containing organic domains that are not miscible together. This is often observed for PDMS-based materials modified with very polar groups that are able to develop supramolecular interactions such as hydrogen bonds or ionic bonds . AFM was conducted on this polymer to investigate whether an organization of the material was detected, but no phase separation could be observed regardless of the magnification used (see Figure S4).…”

“…Not only such networks meet the constraints of materials self-repair mentioned above, but they also open new perspectives in terms of processability and ways to reuse/recycle the materials at its end of life. From a structural point of view, such materials can be prepared by considering various strategies such as the introduction of reversible covalent bonds, − physical interactions, − or a combination of the two. ,− …”

“…The latter then act as robust physical crosslinks comparable to the chemical crosslinks in conventional elastomers or the glassy and/or semicrystalline domains in thermoplastic elastomers, leading to the so-called thermoplastic silicone elastomers or TPSEs. In this context, a variety of noncovalent interactions has been proposed, such as hydrogen bonding, ,− metal-ligand association, − π-stacking, − and ionic pairing. − Tuning the strength of the interaction through chemical design or through an external stimulus alters the connectivity of the physical network and can thus provide self-healing properties to silicone-based materials. This has in particular been shown with hydrogen bonding with numerous stickers of different strengths.…”

Synergistic Self-Healing Enhancement in Multifunctional Silicone Elastomers and Their Application in Smart Materials

“…Supramolecular silicones often incorporate other structural segments capable of supramolecular interactions, including π – π stacking and host–guest interactions. A recyclable siloxane elastomer (H-PDMS-Py m ) ( Scheme 26 ), self-healing through a system of combined strong and weak hierarchical hydrogen bonds between urea groups and urethane groups, incorporated additionally pyrene chromophores [ 68 ]. The strong π–π interactions due to Py groups stacking enhanced microphase separation in H-PDMS-Py m .…”

Room-Temperature Dynamic and Creep-Resistant Covalent Adaptive Networks via Phase-Locked Benzimidazole Urea Bonds: Toward Recyclable Elastomers for Wearable Electronic Devices

“…Elastomers are widely used as substrates for fabricating flexible electronic devices − as they possess excellent resilience performance and allow for excellent conformal contact with the body or internal organ surfaces to enable strain sensing with high sensitivity for potential applications in soft robotics, human–machine interfaces5, − and healthcare. − Electronic waste generated after service failure from wearable flexible devices causes serious pollution and has attracted widespread attention and deserves to be disposed of. Thermoplastic elastomer − with physical cross-linking via supramolecular interaction such as hydrogen bonding, − metal coordination, − and ionic interaction or microphase separation structures combined − by these interactions have been widely employed to fabricate healable and recyclable wearable electronic devices, but at the expense of sacrificing the resilience performance and creep resistance which has a big influence on the sensitivity and service stability of the fabricated devices. Chemical cross-linking of the elastomer via covalent bonds is capable of improving the resilience and dimension stability, but the challenge remains in achieving the recycling of the devices after service failure.…”