Surface modification of YS-20 with polydopamine for improving the tribological properties of polyimide composites

Recently, great effort has been devoted to prepare various reinforce fillers to improve polymer performances, but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites. Herein, we engineer raw polyimide (PI) powders with the assistance of polydopamine (PDA) in aqueous solutions. After the modification, polymer powders change from hydrophobic to hydrophilic, which makes it is possible to further modification of polymer powders in liquid phase. During the curing process of modified polymer powders, the partial dehydration of the catechol groups and crosslinking of PDA via C-O-C bonds are confirmed. Based on the features of PDA, a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes (MWCNTs) in polymer matrix. In comparison with ball milling method, this way can preserve the integrated innate structure of MWCNTs effectively. Besides, by taking full advantage of the reducing and metal-coordination capability of PDA, Cu2+ is successfully loaded onto the surfaces of polymer powders. The related characterizations demonstrate that Cu(2+)in situ converts to metallic copper rather than copper oxide during the hot pressing process. The tribological properties of corresponding polymer composites are also studied. These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect.

Automated summary

In this study, polyimide powders are engineered through the assistance of polydopamine in aqueous solutions, leading to the transformation from hydrophobic to hydrophilic properties and enabling further modification. The use of polydopamine allows for the homogeneous dispersion of multi-walled carbon nanotubes in the polymer matrix, while also successfully loading Cu2+ onto the surfaces of the polymer powders, which converts to metallic copper during the hot pressing process. These modifications present multi-profit and practical application prospects for polymer composites.