Work

Formation of micropillars on etched calcite and their biomimetic effect on wettability: Implications for built heritage protection

Year: 2025

Type: article

Abstract: We demonstrate the possibility of biomimetically altering the wettability of calcite (CaCO 3 ) surfaces by the formation of micropillars through anisotropic dissolution with ammonium chloride (NH 4 Cl) solutions. In situ atomic force microscopy (AFM) analysis of the dissolution of (104) calcite faces shows that the ammonium salt solution induces the nucleation of multiple distorted rhombohedral etch pits (with rounded obtuse steps due to interaction with ammonium ions) that deepen and spread at slower rates than in water. Their coalescence results in dense arrays of c -axis oriented pyramidal micropillars (∼15–30 μm height; ∼3–7 μm width at their base) with { 1 ¯ 02 } polar faces stabilized by interaction with ammonium ions. This etching mechanism for micropillar formation is consistent with the computer simulated dissolution process. Micropillar formation on (104) calcite increases the water contact angle from ∼ 60° to ∼ 140°, a value consistent with simulations using the Cassie-Baxter model. These results demonstrate that the treated calcite surfaces achieve near superhydrophobicity. This simple etching strategy has great potential as an effective biomimetic surface treatment to improve the weathering resistance of carbonate stones, such as limestone and marble, and other carbonate-rich materials used in statuary and the built heritage, as well as in modern construction.

Source: Materials & Design

DOI: 10.1016/j.matdes.2025.114214

Authors: Francesco Santoro De Vico, Kerstin Elert, Encarnación Ruiz-Agudo, Carlos Rodriguez-Navarro

Institutions: Consejo Superior de Investigaciones Científicas, Escuela de Estudios Árabes, Universidad de Granada

Language: English

Topic: Surface Modification and Superhydrophobicity

Subfield: Surfaces, Coatings and Films

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,650