Waterborne polymers are vital for coating industry to reduce carbon emissions.However,formation of robust and self-healable films at ambient temperature remains a challenge owing to high energy cost of film formation ...Waterborne polymers are vital for coating industry to reduce carbon emissions.However,formation of robust and self-healable films at ambient temperature remains a challenge owing to high energy cost of film formation process.This work reports a solar-driven film formation of waterborne polyurethanes(WPUs)containing disulfide bonds via in-situ incorporation of 2D titanium carbide(MXene)with ability to convert light to heat.Instead of directly mixed with WPUs,MXene is added to join the reaction with isocyanate-terminated pre-polymer before emulsification process.This approach not only prevents aggregation of MXene in water but stabilizes MXene against thermal degradation which is the key hurdle for mass production of MXene/WPU composites.More importantly,our results show that mechanical performance of WPU films under visible light(100 mW/cm^(2))is overwhelmingly competitive with that processed in oven.Furthermore,the existence of disulfide bonds in PU chains enables fast self-healing of micro-cracks under natural visible light which could vanish completely within 40 min.The fractured specimens were repaired under natural visible light for 2 h,and the self-healing efficiency of tensile strength and elongation at break reached over 94.00%.展开更多
基金National Natural Science Foundation of China(Grant No.21503110)for supporting this work.
文摘Waterborne polymers are vital for coating industry to reduce carbon emissions.However,formation of robust and self-healable films at ambient temperature remains a challenge owing to high energy cost of film formation process.This work reports a solar-driven film formation of waterborne polyurethanes(WPUs)containing disulfide bonds via in-situ incorporation of 2D titanium carbide(MXene)with ability to convert light to heat.Instead of directly mixed with WPUs,MXene is added to join the reaction with isocyanate-terminated pre-polymer before emulsification process.This approach not only prevents aggregation of MXene in water but stabilizes MXene against thermal degradation which is the key hurdle for mass production of MXene/WPU composites.More importantly,our results show that mechanical performance of WPU films under visible light(100 mW/cm^(2))is overwhelmingly competitive with that processed in oven.Furthermore,the existence of disulfide bonds in PU chains enables fast self-healing of micro-cracks under natural visible light which could vanish completely within 40 min.The fractured specimens were repaired under natural visible light for 2 h,and the self-healing efficiency of tensile strength and elongation at break reached over 94.00%.
