Waterborne polyurethane (WPU) is a versatile and environmentally friendly polymer that has found applications in various industries such as coatings, adhesives, and textiles. One of the key components in WPU synthesis is the chain extender, which determines the properties of the final product. In this blog post, we will explore the synthesis, characterization, and application of a novel sulfonic acid type water-based polyurethane chain extender.
Synthesis of Sulfonic Acid Type Chain Extender
The sulfonic acid type chain extender, N,N’-bis(2-hydroxyethyl)-2-aminopropane sulfonate, was synthesized through a radical addition reaction. The starting material, N,N’-bis(2-hydroxyethyl)-2-amine propenyl, was sulfonated using sodium bisulfite and sodium sulfite as the sulfonating agents. The reaction conditions were optimized to achieve the highest sulfonation degree, which was found to be 94% when the reaction temperature was 90°C, the reaction time was 8 hours, and the molar ratio of N,N’-bis(2-hydroxyethyl)-2-amine propenyl to sodium bisulfite was 1:2.5.
Characterization of the Sulfonic Acid Type Chain Extender
The synthesized sulfonic acid type chain extender was characterized using various techniques. Nuclear magnetic resonance (NMR) and infrared spectroscopy (FTIR) were used to confirm the structure of the product. Elemental analysis was performed to determine the elemental composition of the chain extender. X-ray diffraction (XRD) was used to investigate the crystallinity of the product, and thermogravimetric analysis (TGA) was used to evaluate its thermal stability. The results indicated that the product had a high degree of crystallinity and good thermal stability.
Application of Sulfonic Acid Type Water-Based Polyurethane
The sulfonic acid type chain extender was used to synthesize sulfonic acid type water-based polyurethane (SWPU) and carboxylic acid type water-based polyurethane (CWPU) by incorporating it as a hydrophilic chain extender. The properties of SWPU and CWPU were compared, and it was found that SWPU exhibited better hydrophilicity, heat resistance, solid content, and stability compared to CWPU. This is due to the stronger hydrophilicity of the sulfonic acid group compared to the carboxylic acid group, which leads to a higher degree of ionic interaction and better dispersion in water.
Conclusion
The synthesis, characterization, and application of the sulfonic acid type water-based polyurethane chain extender demonstrated its potential as a valuable component in the production of high-performance waterborne polyurethane materials. The superior properties of SWPU compared to CWPU highlight the importance of choosing the right chain extender for achieving desired material properties.