UV-curable waterborne polyurethane from CO2-polyol with high hydrolysis resistance

Abstract

Abstract UV-curable waterborne polyurethanes (CO 2 -UV-WPUs) with CO 2 -polyols as soft segment were firstly synthesized. In addition to the good mechanical performance, the coexistence of carbonate and ether moieties in soft segment assured the excellent hydrolysis resistance of CO 2 -UV-WPU compared with polybutylene adipate glycol based waterborne polyurethane (PBA-UV-WPU). Its retention of tensile strength reached 88% after 15 h immersion in 1.5% sodium hydroxide solution, while that of PBA-UV-WPU completely lost its mechanical property. The double bond density primarily governed the mechanical performance of CO 2 -UV-WPU, when it increased from 0.93 mmol/g to 2.4 mmol/g, the tensile strength increased from 29 MPa to 67 MPa, while elongation at break decreased from 150% to 9.6%, accompanied by the reduction of maximum water swelling percentage from 26.7% to 14.5%. The introduction of CO 2 -polyol as soft segment not only created a route to produce UV-curable waterborne polyurethane from CO 2 , but also provided polyurethane with novel value-added performance like good hydrolysis resistance. Moreover, the thermal/mechanical performance and hydrophilicity of CO 2 -UV-WPUs could be conveniently adjusted by controlling molecular weight of CO 2 -polyols, ensuring the application feasibility of CO 2 -UV-WPU.