Soft Segment‐free Functional Polyurethane: A Versatile Candidate for Heat‐healability, Non‐dissociative Mechanism, and High Elongation Adhesive Materials

Functional and re-processable polyurethane (soft-segment free, FPU) is synthesized and later it is converted into substituted PUs by reaction with suitable molecules to enrich/block H-bonding features inherent with FPU. By these substitutions, H-bonding is easily altered as observed in FTIR investigations. Spherical morphology of FPU turned into elongated/twisted one due to the separation of polymer chains by these molecules (bulky or long chain groups). Owing to the presence of hydroxyl groups, the dissociation of FPU on re-processing at 150 degrees C was dodged and achieved heat-healable PUs. Interestingly, a trivial quantity (2.5 wt%) of FPU in an epoxy-amine cross-linked structure increased the elongation to nearly fourfold (5%-21%). The soft-segment free nature of PU and its functional groups have key role in facilitating easy incorporation of PU into epoxy matrices to provide exotic properties.