Abrasion resistance of waterborne polyurethane films incorporated with PU/silica hybrids

• Sol–gel derived MTES modified silica nanoparticles were dispersed uniformly in films.
• Composite films containing MTES modified silica showed superior abrasion resistance.
• Abrasive wear occurs was proved during the abrasion resistance test.
• Surface morphology analysis demonstrated the results of abrasion resistance test.

We describe polyurethane (PU)/silica hybrids (PSHs) prepared through hydrolysis and condensation reactions of tetraethoxysilane (TEOS) with or without methyltriethoxysilane (MTES) in the presence of polyurethane dispersion, which were subsequently incorporated into waterborne polyurethane (WPU) to prepare composites. The effects of the solid mass ratio of PSHs/WPU on the particle size of composite emulsions, the dispersion of silica nanoparticles in composite films, and the hardness and abrasion resistance of the corresponding films were examined. Composite emulsions possess a nanoscale particle size when incorporated with PSHs prepared using TEOS and MTES as precursors, and are superior to those with PSHs prepared using TEOS alone. Transmission electron microscopy revealed that silica nanoparticles had a uniform distribution in the polymer matrix and agglomerates could be almost completely avoided through in situ modification of silica with Si-CH3 groups in the polyurethane dispersion. Composite films prepared with this method exhibited a superior hardness and abrasion resistance even at a lower silica content compared with that containing unmodified silica. In particular, optical microscopy and scanning probe microscopy observations demonstrated wear behavior differences among these composite films from the macro- and nanoscale viewpoints, respectively. It is proved that abrasive wear occurs, and surface morphology studies are in accordance with the results of abrasion resistance tests.

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