Facile preparation and characterization of low-gloss waterborne polyurethane coatings using amine-based chain extenders

A novel waterborne polyurethane (WPU) coating with a self-roughed surface is prepared using a general prepolymer emulsion polymerization method. A rough surface is formed by crosslinking the WPU particles through the introduction of a polyfunctional amine-based chain extender. Ethylenediamine, diethylenetriamine (DETA) and triethylenetetramine (TETA) with different functional groups are used as chain extenders, and their effect on the surface morphology and gloss of WPU films is investigated. DETA and TETA form a rough surface on the WPU film by crosslinking the polymer chains and promoting phase separation between soft and hard segments. A rough surface reflects light diffusely, resulting in a decrease in the gloss of the film. Overall, the chain extension improves the thermal stability and tensile strength of the WPU film. In particular, the WPU film with DETA, exhibiting the highest chain extension effect, shows the lowest gloss value, the highest tensile strength and thermal stability. The present series of WPU materials, prepared without matting agents and special treatment processes, can be an effective alternative for producing low-gloss coatings. © 2022 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.