A Stretchable and Rapidly Self-Healable Polysiloxane Elastomer Based on Reversible Ionic Hydrogen Bonds

A series of linear poly(dimethylsiloxane) (PDMS-g-Vi) with different vinyl contents were synthesized via ring-opening copolymerization of tetravinyltetramethylcyclotetrasiloxane (V₄) and octamethylcyclotetrasiloxane (D₄) catalyzed by a cyclic trimeric phosphazene base (CTPB). Further, the carboxylic acid- or amine-functionalized PDMS (PDMS-g-COOH and PDMS-g-NH₂) was prepared through the thiol-ene click reaction, confirmed by gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (¹H-NMR). Finally, the target silicone elastomers (PDMS-g-COOH/NH₂) were prepared based on the reversible ionic hydrogen bonds between COOH and NH₂ side chain groups, exhibiting remarkably fast self-healing capability at room temperature without any external stimulus. The mechanical strength, elasticity and self-healing properties of resultant elastomers could be tuned by modulating the hydrogen bonding density and the molecular weight of PDMS-g-Vi precursors. The PDMS-g-COOH/NH₂ elastomer owned a breaking stress of 230.9 kPa at 877% elongation at break with a stretching speed of 50 mm/min, and the elongation at break was higher than 500% even under a fast stretching speed (200 mm/min). Moreover, its self-healing efficiency reached as high as 99% after being restored at room temperature for 30 min.