Facile synthesis amide‐functional anionic chain extenders for enhanced thermal stability and emulsion performance in waterborne polyurethanes

Abstract While increasing the number of these extenders improves the stability of the waterborne polyurethane (WPU) emulsion, it also decreases the thermal stability of the WPU film, creating a challenge that needs to be addressed. In this study, a class of scalable anionic chain extenders featuring amide functional groups is thoughtfully designed for industrial applications. Diethanolamine reacts with various anhydrides, serving as an internal emulsifier in WPU production. The prepared WPU features a narrow particle size distribution, averaging between 100 and 250 nm, resulting in excellent stability even after centrifugation at 3000 rpm. Introducing an amide‐functional emulsifier into the WPU structure improved thermal stability, with T5 wt% ranging from 276.5 to 293.1°C. Mechanical test results indicate that the WPU1 film demonstrates impressive mechanical performance, featuring a tensile strength of 13.55 MPa and an elongation at a break of 980%. The resulting WPU films show strong adhesion to different surfaces, with lap shear strength for carbon steel varying from 4.67 to 5.14 MPa. This presents an innovative approach to balancing the emulsifying capability with the water resistance feature of WPU. This study offers a promising alternative to DMPA, emphasizing its potential for future use in WPU industrial production and applications. Highlights Synthesis of amide‐functional anionic chain extenders. Enhanced thermal stability and emulsion performance. WPU with optimized colloidal characteristics. WPU films with enhanced thermal stability. A viable alternative to 2,2‐dimethylpropionic acid‐based systems.