High-transparency, weather-resistant nanocomposite coatings from a shear-aligned 2D unit-cell-thick perovskite for wooden artifact preservation

Abstract

Preserving wooden artifacts is crucial for protecting cultural heritage, but these materials are particularly susceptible to environmental damage, especially from moisture and corrosion. Traditional waterborne acrylic coatings, while environmentally safe and widely used in cultural relic preservation, lack the necessary mechanical strength and water resistance. These limitations often lead to issues such as cracking and whitening, necessitating frequent replacement and complicating the conservation process. To address this issue, in this study, a “brick-and-mortar” structure with a “labyrinth effect” was introduced into waterborne acrylic resins to synergistically enhance their toughness and water-resistance. The nanocomposite coatings, named PNS-AR, were prepared through a shear-alignment and rapid-drying approach, where highly exfoliated unit-cell-thick Ca₂Nb₃O₁₀ perovskite nanosheets (PNSs) were incorporated into an acrylic resin matrix, creating a well-ordered “brick-and-mortar” structure. The excellent transparency of the unit-cell-thick PNS nanosheet and its alternating layered arrangement within the resin matrix impart the nanocomposite coatings with enhanced transparency. This structural alignment also enhances stress transfer, significantly boosting mechanical strength and toughness. At a PNS content of 3 wt%, the coating achieved the maximum tensile strength (8.52 MPa), elastic modulus (436 MPa), and toughness (0.2 MJ m⁻³), representing increases of 432.5%, 166.2%, and 458.5%, respectively, compared to the pristine AR coating. The water absorption and soaking experiments demonstrate the PNS-AR coating's excellent moisture resistance, with water absorption decreasing from 25 wt% to 8.1 wt% with 4 wt% PNS and transparency largely maintained after 24 hours in deionized water. Additionally, the weather-resistance properties of PNS-acrylic nanocomposite coatings offer a durable and effective solution for the long-term preservation of wooden artifacts, enhancing resistance against diverse environmental degradation.