An insight on the effect of the hard segment domain on the thermo‐mechanical and surface properties of new piperazine‐based polyurethanes

Abstract

Abstract1,4‐piperazinediethanol was used as chain extender in the synthesis of new polyurethanes based on poly (tetramethylene oxide) glycol and 1,6‐hexamethylene diisocyanate. Also new polyurethanes which contain renewable cross‐linkers (polyethylene glycol sorbitan monolaurate (Tween® 20) and sorbitan monolaurate (Span® 20)) were obtained. The degree of microphase separation and the weight fraction of hydrogen‐bonded urethane groups is calculated by FTIR spectroscopy. The thermal, mechanical, and surface properties are examined and related with the structure of the corresponding polyurethanes. Linear polyurethanes have good thermal stability with the 5% weight loss in the range 250–280°C and cross‐linked samples in the range 295–320°C. Tensile strength and elongation at break have higher values (38 MPa and 1140%) when the 1,4‐piperazinediethanol content is lower. The increase in the piperazine content leads to more hydrophilic polyurethane surface. Cross‐linkers increase the water contact angle and thus the surface of the corresponding polyurethanes becomes hydrophobic.