Synthesis of high-toughness waterborne polyurethane utilizing self-emulsifying CO2-based polyols

In this work, a self-emulsifying CO 2 -based polyol (LAPEC) was prepared by the terpolymerization of propylene oxide , allyl glycidyl ether and CO 2 , followed by thiol-ene click reaction with mercaptopropionic acid. And the carboxyl group was successfully introduced into LAPEC verified in 1 H NMR. LAPEC was served as both soft segments and internal emulsifiers for WPU . Meanwhile, γ-aminopropylmethyldiethoxysilane (KH902) was also employed to improve the mechanical properties of WPU . Compared to dimethylol propionic acid (DMPA), WPU emulsion prepared by LAPEC had smaller particle size and higher emulsification efficiency. And the performance differences between LAPEC-based WPU films (LWPUs) and DMPA-based WPU films (DWPUs) with different hard segment contents were studied. The stronger hydrogen-bonding interactions improved the tensile strength , toughness and thermal stability. Compared with DWPU, the tensile strength and the elongation at break of LWPU respectively increased from 17.8 to 21.1 MPa and from 302.3 % to 356.5 %, when their hard segment content was both maintained around 37 wt%. Meanwhile, due to rougher surfaces and more hydrophobic silicon clusters, LWPU had stronger surface hydrophobicity . Therefore, LAPEC can provide a new way to synthesize WPU with high toughness and can be potentially used for flexible substrate coatings in the future.