Abstract: Plant-oil-based waterborne polyurethanes were synthesized by using polyether-polysiloxane polyols (PEPSO) and castor oil as raw materials. In the synthetic process, different amount of PEPSO was introduced into polyurethane molecular chains through a chemical reaction between NCO groups and OH groups of PEPSO, which resulted in a series of polyurethane emulsions with different contents of PEPSO soft segments. Chemical structures, particle size, thermal stability, mechanical properties and surface hydrophobicity of the prepared polyurethanes were extensively characterized. The results indicated that PEPSO segments were successfully incorporated into polyurethane backbones, and the resultant polyurethanes exhibited an enhanced thermal stability in the presence of PEPSO segment. However, the glass transition temperature and particle size of polyurethanes were reduced with increasing content of PEPSO segment. With the addition of small amount of PEPSO, the tensile strength and hydrophobicity of polyurethanes was improved to some extent.

Key words: polyether-polysiloxane, castor oil, plant oil-based waterborne polyurethane, hydrophobicity