Fig. 3. Improved toughness and mechanical stability of the hybrid coating.

a Schematic illustration of supramolecular interactions in the hybrid nanofilm. b The deconvoluted IR bands to characterize hydrogen bonding in the hybrid nanofilms. c ΔD–ΔF plots from Quartz crystal microbalance with dissipation (QCM-D) indicating the viscoelastic properties of the adsorption layer. d, e Stress–strain curve (d), fracture stress and toughness (e) of the PTB and PTB@SA(0.10) nanofilm recorded at 22 °C and 50% relative humidity. Data are mean ± S.D. n = 3 independent samples per group. f, g Loading–unloading curves of PTB and PTB@SA(0.10) nanofilms (f) and corresponding elastic modulus and hardness (g), as determined by nanoindentation tests. Data are mean ± S.D. n = 4 independent samples per group. h–k Scanning electron microscope (SEM) images of the PTB or PTB@SA(0.10)-modified SR after the fatigue bending test, respectively. Yellow arrows indicate cracks. The experiments in (h–k) were repeated independently at least three times with similar results. Statistical significance was determined by two-tailed Student’s t-test (e and Hardness in g) or two-tailed Welch’s t-tests (Elastic modulus in g). Source data are provided as a Source Data file.