A calixarene derivative, 5,11,17,23-tetrakis (hydroxyl ethyl sulfonamide) calix [4]arene, was synthesized through a linear reaction from parent calix [4]arene. This sulfonamide calixarene derivative was used as a precursor to produce calixarene-polyurethane composite. Structural properties of calixarene-based synthesized precursors were studied using spectroscopic techniques such as 1 H-NMR, 13 C-NMR, and IR. Also, mechanical properties of produced polyurethane composite such as fracture elongation, modulus, and tensile strength were studied which indicated that these properties were deeply dependent upon calixarene ratio in composite. An increase in calixarene ratio resulted in a decrease the fracture elongation. In contrast, an increase in calixarene ratio caused a considerable decrease of modulus and tensile strength. The modulus and tensile strength were increased by 16.98 and 20 % as the calixarene/polyol ratio reached 3 %. Finally, TGA and DSC studies showed that calixarene ratio considerably enhanced the thermal stability of polyurethane.

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Summary Calix[4]arenes namely, 5,11,17,23 tetra tert butyl calix[4]arene and 5,11,17,23 tetra chlorosulfonyl calix[4]arene were synthesized to produce octakis (hydroxyl ethyl) sulfonamide calix[4]arene which was used in polyurethane‐calixarene rigid foam composite formulation. The effect of calixarene ratio on mechanical properties of synthesized composites was studied at three calixarene ratios including 1.5, 2, and 3 % (w/w). The obtained data indicate that the tensile strength and modulus are increased as the calixarene ratio increases while the fracture strain is decreased. Quantitatively, addition of 3% (w/w) of calixarene to the polyurethane resulted in 30.99% and 30.01% improvements in modulus and tensile strength, respectively. Contrarily, a decrease of about 13.1% was observed in fracture strain when compared to the properties of the pristine polyurethane rigid foam. The effect of Calixarene on thermal stability of Calixarene‐ polyurethane composite indicating that Calixarene component strictly enhances the thermal stability of composite.