Mechanically Strong, Autonomous Self‐Healing, and Fully Recyclable Silicone Coordination Elastomers with Unique Photoluminescent Properties

Abstract

The combination of excellent mechanical performances, high reprocess efficiency, and wide-range tunability for functional dynamic siloxane materials is a challenging subject. Herein, the fabrication of mechanically strong, autonomous self-healing, and fully recyclable silicone elastomers with unique photoluminescent properties by coordination of poly(dimethylsiloxane) (PDMS) containing coordination bonding motifs with Zn 2+ ions is reported. Salicylaldimine groups, which are introduced into the polysiloxane backbone via mild Schiff-base reaction, coordinate with zinc ions to form elastomeric networks The obtained supramolecular elastomers have excellent mechanical properties, with the optimized tensile strength up to 10.0 MPa, which is unprecedented among the reported thermoplastic polysiloxane-based elastomers. Both mechanical properties and stress relaxation kinetics are tunable via adjusting the length of PDMS segments or the molar ratio of metal versus salicylaldimine. Furthermore, these elastomers can be conveniently healed and recycled to regain their original mechanical properties and integrity under mild conditions. In addition, this new kind of polysiloxane also exhibits coordination-enhanced fluorescence, showing great promise for preparing photoluminescent elastomers or coatings.

Second Natural Rubber with Self-Reinforcing Effect Based on Strain-Induced Crystallization

“…As shown in Figure 5d, EEUG-17.4%-DTSA-2 became more whitish when it was stretched to a strain of 1000%, suggesting the formation of crystals at high strain. 34 The energy dissipation of EEUG-17.4%-DTSA-2 at different strains was characterized by using cyclic tensile tests with an increasing strain but no delay time 45 SBR/PEI interlocked networks, 28 PU (hydrogen bonds), 46 PB dual network, 25 ENR/chitosan, 47 ENR/cellulose, 48 MIVs (mechanically interlocked vitrimers), 49 and SBR-M.HPDI.Upy dynamic liquid crystal networks. 50 (Figure 5e), and the hysteresis area represents the dissipated energy during each cycle.…”

“…(a) Stress−strain curve and (b) cyclic tensile−strain curves of EEUG-14.5%-DTSA-2, EEUG-14.5%-DTSA-3, and EEUG-17.4%-DTSA-2. (c) Comparison of mechanical properties with other recyclable elastomers: PDMS-Zn,45 SBR/PEI interlocked networks,28 PU (hydrogen bonds),46 PB dual network,25 ENR/chitosan,47 ENR/cellulose,48 MIVs (mechanically interlocked vitrimers),49 and SBR-M.HPDI.Upy dynamic liquid crystal networks 50. (d) Digital images showing the whitening process of the EEUG-17.4%-DTSA-2 at strain from 0 to 1000%.…”

Healable and Recyclable Polymeric Materials with High Mechanical Robustness

“…Host–guest interactions is defined as the force that binds the macrocyclic host molecules and specific guest molecules internally to form an inclusion complex (Figure a) . Scherman and co-workers reported a self-healing supramolecular hydrogel obtained by in situ polymerization of acrylamide and a kind of functional monomers complexed with the host molecules of cucurbit[8]­uril (CB[8]). , Metal ions can form reversible coordination interactions with the corresponding ligands (Figure a). , Rowan and co-workers developed healable polymers based on metal–ligand coordination interactions, which were prepared by grafting ligands on the ends of the poly­(ethylene- co -butene) chains followed by coordination with Zn 2+ . The mechanical properties and healing performance of the metallosupramolecular polymers can be tailored by replacing Zn 2+ with other metal ions.…”

Bioinspired Rubber Composites with Mechanical Robustness, Recyclability, and Shape Memory Properties

“…[11] Considering the engineering requirements of rubber composites on reinforcement, recycling and functionality, it remains quite a challenge to explore more strategies in preparing rubber vitrimers. [12][13][14] In recent years, the engineering of sacrificial and reversible bonds (hydrogen bond, ionic bond or metal coordination bond) into elastomers has shown tremendous potential for achieving reinforcement and multiply functions, for example, shape memory, self-healing and sensing properties. [15][16][17][18][19][20][21] Different from other dynamic sacrificial bonds, coordination bonds not only are switchable but also possess bond strength that can rival typical covalent bonds, which have become the best alternative to the exchangeable covalent bonds in preparing vitrimer-like rubber materials.…”

“…[ 11 ] Considering the engineering requirements of rubber composites on reinforcement, recycling and functionality, it remains quite a challenge to explore more strategies in preparing rubber vitrimers. [ 12–14 ]…”