Polyurethane functionalized with pendant furan moiety (FPU) was prepared using a novel chain extender (FA-FGE) which was obtained from the reaction between furfurylamine (FA) and furfuryl glycidyl ether (FGE). This furan containing PU (FPU) was grafted with maleimide functionalized polyhedral oligomeric silsesquioxanes (POSS maleimide isobutyl, POSS-M) via Diels− Alder (DA) "click" reaction. The resultant DA adducts of FPU-POSS-M hybrid material showed a remarkable increase in water contact angle (WCA) from 84°to 141.3°. This remarkable increase in the WCA is due to the combined effect of the grafting of hydrophobic POSS-M units as well as the increased micro-and nanoscale surface roughness, as evidenced by AFM and FESEM analyses. The self-healing characteristic of this organic−inorganic hybrid was evaluated by the tensile test as well as by monitoring the disappearance of the crack using optical microscopy. The formation of FPU-POSS-M hybrid material was confirmed by GPC, FT-IR, and 1 H NMR analyses, and their thermoreversible nature was confirmed by DSC analysis. The tensile strength and tensile modulus of the FPU-POSS-M hybrid film were much higher than those of pristine FPU. The surface hardness and the penetration depth of the nanoindent in FPU and FPU-POSS-M hybrid coating were evaluated using the nanoindentation experiment. The adhesion property of the hybrid material with the metal surface was studied by lap shear test. TGA analysis showed a significant improvement in thermal stability of the FPU-POSS-M hybrid material. This self-healable and ultrahydrophobic FPU-POSS-M hybrid material can be used in specialty coating application.

Polyurethane (PU) with an ionic liquid crosslinker (with a unique double network having a combination of covalent as well as ionic crosslinking) showed excellent shape-recovery as well as excellent shape-fixity properties compared to linear PU and non-ionic crosslinked PU. The non-ionic crosslinker resulted in hard and soft phases intermixing, whereas the ionic interaction in ionic liquid crosslinked PU kept the phase separation intact.

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, E σ ≈ 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.

A novel flexible polyurethane was prepared using ionic liquid as crosslinker. It showed lower Tg, superelastomeric behavior with very high elongation, better tensile and oil resistance properties than a non-ionic crosslinked PU or a linear PU.