Surface hydrophobic modification of polyurethanes by diaryl carbene chemistry: Synthesis and characterization

摘要

Graphical abstractDisplay OmittedHighlights•Dodecyl diaryl diazomethane could generate carbene by solar-light exposure.•Water-borne polyurethane film could be well modified by carbene insertion reaction.•The surface property of the film was changed from hydrophilicity to hydrophobicity.•The hydrophobic modification would protect polyurethane film from moisture.AbstractDodecyl diaryl diazomethane was firstly synthesized from 4,4-dihydroxybenzophenone and 1-bromododecane by a series of reaction steps. Then water-borne polyurethane films with different amount of DMPA were prepared, as well as a type of solvent-borne polyurethane film for comparison. Finally, all these polyurethane films were modified by dodecyl diaryl diazomethane. The dodecyl diaryl carbene was generated from dodecyl diaryl diazomethane by strong solar light, which was very convenient to insert into the XH bonds (X = C, N) on the surface of polyurethane films. The contact angle test was used to characterize these films and depict the surface property. DSC analysis and tensile test were used to investigate the physical properties of polyurethane films before and after modification. It was suggested that the hydrophobic modification protocol with carbene insertion was very useful and convenient to prepare water-proof coatings outdoors under direct solar-light exposure.