Research Information System
PROGRESS IN ORGANIC COATINGS, 2025 (SCI-Expanded, Scopus)
This study examines the influence of gradient nanocomposite coatings on the surface mechanical properties of soft composite substrates (modulus: 150 MPa). Polyvinylpyrrolidone reinforced with halloysite nanotubes was used to fabricate gradient (e.g. 5/15/30 wt%) and reverse gradient (e.g. 30/15/5 wt%) coatings for comparative analysis. Reverse gradient coatings consistently exhibited superior surface properties, particularly in thicker (30 mu m) systems, where stiffer sublayers effectively transferred stress to the surface. The 30/15/5 reverse gradient coating achieved a modulus of 2.92 GPa, significantly outperforming its gradient counterpart (0.33 GPa) at similar indentation depths. In contrast, thinner (15 mu m) gradient coatings with smaller concentration variations (5/10/15 wt%) facilitated a significantly smoother mechanical transition and improved stress distribution, while larger concentration differences (5/15/30 wt%) amplified substrate effects, increasing indentation depth. These findings highlight the trade-offs in coating design: gradient coatings optimize mechanical transitions, making them ideal for functional interfaces and load-distributing layers, while reverse gradient coatings ensure greater mechanical consistency, making them suitable for protective and structural applications requiring enhanced surface durability.