Synthesis and characterization of waterborne polyurethane based on covalently bound dimethylol propionic acid to e-caprolactone based polyester polyol

• In this paper, liquefiable dimethylol propionic acid (LDMPA) was designed by the condensation of ε-caprolactone(CL) with dimethylol propionic acid (DMPA).
• A series of waterborne polyurethanes (WPU) were successfully synthesized by using LDMPA.
• The structure and properties of the WPU were studied.
• The influence of LDMPA on the properties of WPU was investigated, while WPU synthesized by using DMPA was used as a comparison.

In this paper, a low temperature liquefiable dimethylol propionic acid (LDMPA) was designed by the condensation of ε-caprolactone(CL) with dimethylol propionic acid (DMPA). A series of waterborne polyurethanes were successfully synthesized by using LDMPA. The structure and properties of the waterborne polyurethanes were characterized by IR, particle size analysis and tensile tests. It was found that with increasing LDMPA content, the particle size of the waterborne polyurethane emulsion decreased. The results of tensile tests showed that with increasing LDMPA content, the tensile strength and elongation at break of the samples increased at first and then deceased. DMA results showed that compared with samples using dimethylol propionic acid (DMPA), the introduction of LDMPA into WPU chain could reduce waterborne polyurethane’s micro-phase separation degree.