Supramolecular Polydimethylsiloxane Elastomer with\nEnhanced Mechanical Properties and Self-Healing Ability Engineered\nby Synergetic Dynamic Bonds

Abstract

Hydrophobic\nelastomers are required for use in industry and daily\nlife because of their versatile properties. Developing a hydrophobic\nelastomer with self-healing abilities and excellent mechanical performance\nhas been very challenging because of the mutually exclusive nature\nof these properties. Herein, supramolecular polydimethylsiloxane (PDMS)\nelastomers with excellent self-healing and mechanical properties were\ndesigned through the synergetic combination of multistrength H-bonds\nand disulfide bonds. The hierarchical H-bonds formed with urethane,\nurea, and 2-ureido-4­[1<i>H</i>]-pyrimidinone (UPy) moieties\nin the backbone of the supramolecular polymer endow the resultant\npolymers with effective reversible cross-linking, whereas during stretching,\nthe dynamic dissociation and reassociation of H-bonds enable polymers\nwith high extensibility and enhanced toughness and recoverability.\nIn addition, disulfide bond exchange under heat enables polymer network\nrearrangement, thus imbuing the supramolecular elastomer with excellent\nself-healing ability. Based on the extraordinary properties of hydrophobic\nsupramolecular PDMS elastomers, some smart materials can be prepared,\nsuch as oil/water separation foams and hydrophobic hot-melt adhesives.\nTherefore, this concept of synergetic dynamic bonds will point out\na direction for the development of sustainable, green, and functional\nmaterials of the next generation.