Tough omni-dynamic silicone rubbers with excellent self-healing, elasticity, remoldability, and degradability

Abstract

Combining different reversibly connecting mechanisms in a single system constitutes an efficient method to multi-functionalize dynamic polymer materials but normally requires complicated molecular designs. Herein we report a class of omni-dynamic silicone elastomers that can be directly prepared via simple anionic ring-opening polymerization (AROP) of octamethylcyclotetrasiloxane (D4) with bis(tetramethylammonium)oligodimethyl siloxanediolate (BTMASA) as the bifunctional initiator. The polymerization leads to the formation of telechelic polydimethylsiloxanes (PDMS) that would immediately undergo microphase separation to form elastic products. On the one hand, the tetramethylammonium siloxanolate (TMASA) terminals of the telechelic PDMS aggregate into charged domains serving as dissociative supramolecular crosslinking interactions in the products. On the other hand, the TMASA groups maintain their activities after polymerization and can catalyze associative chain exchange reactions among PDMS chains. Such a unique structure endows the silicone elastomers with good solubility in solvents like tetrahydrofuran (THF), appealing mechanical properties (elastic, stretchable, tough), and excellent degradability. In this system, the BTMASA plays multiple roles, including an initiator for AROP, a building block for supramolecular crosslinking, and a catalyst for chain exchange. We believe such a one-to-three concept will open a new direction for the design of novel dynamic polymer materials.