Highly Tough Polyurethane Nanocomposite Reinforced With NH 2 ‐Silane‐Modified Zn–Al‐ LDH Nanosheets

The primary objective of this study was to enhance the mechanical performance of a conventional polyurethane (PU) coating through the incorporation of high‐aspect‐ratio layered nanoparticles. To this end, Zn–Al layered double hydroxide (LDH) nanosheets were synthesized and subsequently surface‐functionalized with 3‐aminopropyltriethoxysilane (APTES) to improve their dispersion within the organic PU matrix and strengthen the interfacial interactions between the nanofillers and the polymer. Both unmodified (ULDH) and silane‐functionalized (LDH@Si) nanosheets were incorporated into the PU matrix at loadings of 1, 2, and 3 wt.%. Mechanical characterization demonstrated that although ULDH enhanced the toughness of the PU matrix at an optimum loading of 2 wt.%, further increases in filler content resulted in inferior mechanical performance due to particle agglomeration and nonuniform dispersion. In contrast, the LDH@Si nanocomposites exhibited a progressive enhancement in mechanical properties with increasing filler content, achieving the highest performance at a loading of 3 wt.%, corresponding to a 165% increase in toughness relative to the neat PU. This remarkable improvement is attributed to the effective reinforcing effect of the silane‐functionalized nanosheets, which promoted both covalent interactions, through an increased crosslinking density, and noncovalent interfacial interactions with the PU network. The enhanced interfacial compatibility imparted by surface functionalization also facilitated a more homogeneous particle distribution throughout the polymer matrix, as corroborated by topographical, surface morphological, and cross‐sectional analyses.