Self-Healable Polyurethane Elastomer Based on Dual Dynamic Covalent Chemistry Using Diels–Alder “Click” and Disulfide Metathesis Reactions
Prasanta Kumar Behera, Sagar Kumar Raut, Prantik Mondal, Shrabana Sarkar, Nikhil K. Singha
Abstract
Functional polyurethanes have several important advanced applications. In this investigation, a dual-functional polyurethane (PU) elastomer having disulfide as well as furfuryl functionality was developed. For this purpose, a functional diol having furfuryl and disulfide functionality was synthesized and used as a chain extender for the synthesis of a PU elastomer based on polycaprolactone (PCL) diol and 4,4′-methylenebis (phenyl diisocyanate) (MDI). This dual functional PU elastomer was cross-linked using a bismaleimide (BM) via the Diels–Alder (DA) reaction with the furfuryl pendant group in PU. This dual functional PU having thermoreversible DA linkage and disulfide linkage showed excellent tensile strength (σ = 39.5 MPa) and, importantly, good self-healing characteristics (self-healing efficiency, Eσ ≈ 97%). This healable PU having a thermoresponsive as well as a double dynamic covalent system based on the DA reaction and the disulfide metathesis reaction will have potential applications in specialty paints, coatings, and various advanced materials.