Synergistic Inherent and Dynamic Cross-Links for Self-Healable Polydimethylsiloxane Elastomer Foams

Abstract

The preparation of foams with self-healing properties and stable cell structures continues to present significant challenges. In this study, a polydimethylsiloxane elastomer featuring a dual network structure was developed. A dynamic cross-linking network, formed by hydrogen and disulfide bonds, imparted self-healing capabilities to the elastomer. The inclusion of a cross-linking agent created an inherent cross-linking network that improved the mechanical properties and melt strength of the elastomer. The synthesized polydimethylsiloxane elastomer demonstrated an exceptional self-healing performance, achieving a self-healing efficiency of 92.89%, along with impressive mechanical properties, including a tensile strength of 6.32 MPa and an elongation at break of 1277.80%. Additionally, a polydimethylsiloxane elastomer foam with self-healing properties was fabricated using a supercritical carbon dioxide (sc-CO₂) foaming method. With an increase in inherent cross-linking, the cell size decreased from 11.88 to 8.60 μm, while the cell density increased from 2.04 × 10⁹ to 2.71 × 10⁹ cells/cm³, resulting in the uniform cell distribution within the foam. Microcracks in the foam were effectively healed within 10 min at 80 °C, and the cell morphology remained stable after 96 h of exposure to environmental conditions. This dual-network self-healing foam exhibited an excellent self-healing performance along with a stable cell structure.