Synthesis and characterization of cationic waterborne polyurethane elastomer using poly(tetrahydrofuran-co-epichlorohydrin)

This article presents a detailed investigation into the synthesis and characterization of a cationic waterborne polyurethane (WPU) elastomer utilizing poly(tetrahydrofuran-co-epichlorohydrin) as a key component. The study underscores the growing demand for waterborne alternatives to solvent-based polyurethanes, driven by stricter environmental regulations and the need to reduce volatile organic compounds (VOCs). The synthesis process involves cationic ring-opening polymerization of tetrahydrofuran (THF) with epichlorohydrin (ECH) as an initiator, resulting in a copolymer that serves as a high-performance polyether polyol. This polyol is then used to prepare a WPU dispersion via a prepolymer technique, incorporating isophorone diisocyanate (IPDI) and N-methyl diethanolamine (NMDEA) as the diisocyanate and hydrophilic chain extender, respectively. The resulting WPU dispersion exhibits excellent stability, with an optimal polyol/internal emulsifier ratio of 1:2, and an average particle size of 105 nm. The elastomer demonstrates superior mechanical properties, including a tensile strength of 1.84 MPa and an elongation at break of 247%, indicating its suitability for applications requiring moderate-to-high elongation. Additionally, the elastomer shows remarkable thermal stability, with a two-stage degradation profile and a low glass transition temperature, suggesting high flexibility and durability. The surface morphology of the elastomer film reveals a textured structure, contributing to its potential use in coatings and other specialized applications.