Self-Healable Silicone Elastomer Based on the Synergistic Effect of the Coordination and Ionic Bonds

Abstract

The construction of silicone elastomers with mechanical strength and a self-healing property can be verified as an effective method by multiple dynamic bond strategies. However, it means that some complex synthesis strategies or small molecules with specific chemical structures are required. So, it is more challenging to construct a kind of polymer matrix with two kinds of interactions by matured methods directly. Herein, we report a dynamic silicone elastomer with two kinds of interactions that was prepared by incorporating a “carboxyl-amino ionic bond” and “carboxyl-Al3+ coordinated ionic bond”. The carboxyl groups are bonded with amino groups and Al3+ ions to form common ionic bonds and coordinated ionic bonds, respectively. The coexistence of these strong and weak ionic synergistic interactions was verified by setting several experiments in spectroscopic analysis and mechanical tests. It was indicated that the carboxyl-Al3+ interactions can improve the mechanical property of this material effectively, while the dense common ionic network between carboxyl and amino groups can maintain the integrity of the dynamic cross-linking network, which may ensure the good recoverability and self-healable ability of the silicone elastomer. Compared with the control samples based on single ionic bonds, the hybrid network exhibited the better mechanical property with an optimistic tensile strength of ∼0.73 MPa and elongation at breaking of ∼548%, and the network also exhibited a good autonomous self-healing ability at a higher temperature (8 h, 80–136% at 60 °C) and a considerable recoverability at a large scale of stretching (∼70% of elongation at break) with a moderate low hysteresis ratio of only 28.7%. We expect this strategy would be beneficial for the expansion of a convenient way of mixing to prepare elastomers with a synchronous mechanical property and self-healing performance by multiple dynamic bond strategies.

pH-Responsive Gelation in Metallo-Supramolecular Polymers Based on the Protic Pyridinedicarboxamide Ligand

“…Inspired by such elegant designs, Guan and co-workers have incorporated weak supramolecular bonds, based on metal–ligand coordination or hydrogen bonds, into the polyacrylate arms of a comb structure with a polystyrene backbone. , The microphase separation of the low glass-transition temperature ( T g ) arm from the high- T g backbone yields high mechanical strength originating from the dispersed hard phase and fast healing by the reversible dissociation of transient bonds within the soft phase . This approach has recently been further expanded by employing orthogonal combinations of more defined transient bonds, even from different natures, but with significantly different lifetimes. − …”

Progress in the design and synthesis of biobased epoxy covalent adaptable networks

“…Thus, non-covalent bonds (such as ionic bonds and hydrogen bonds) with low bond energies have been studied to design self-healable CANs. [109][110][111] For example, Zhou et al prepared a series of biobased dual dynamic networks based on multiple hydrogen bonds and imine bonds from vanillin and ESO. 112 An oligomer with abundant hydrogen bonds and a primary linear backbone was obtained via the ring-opening reactions of ESO with diethylenetriamine, and an amine transesterification reaction occurred between diethylenetriamine and ESO (Fig.…”

Recyclable silicone elastic light-triggered actuator with a reconfigurable Janus structure and self-healable performance

“…Silicone elastomer benefits from a particular chemical structure and exhibits unique physicochemical properties, such as excellent flexibility, remarkable elasticity, high biocompatibility, as well as high and low temperature stabilities, and thus it has been widely used in electronic devices, the automotive industry, medical implants, sealants, and many other fields. 1,2 However, in practical application processes, the elastomer material inevitably bears a periodic tensile and shear action, therefore it is easy to produce internal micro-cracks and then break, reducing the mechanical performance and service life of the material. 3,4 Moreover, permanent cross-linking networks in traditional silicon elastomers hinder their ability to be recycled, causing environmental pollution and the waste of resources.…”