Enhanced Mechanical Stability and Scratch Resistance of Mesoporous Aluminosilicate Thin Films



Mesoporous coatings are widely used in industries such as optics, display technologies, photovoltaics, and bioengineering, due to their attractive properties such as high surface to volume ratio and excellent mass and electron transport characteristics. While structural parameters and material composition can be routinely tailored to the respective applications, improvements of their mechanical properties and robustness, essential for their long-term performance, remain a challenge. Herein, we provide a comprehensive study on the relationship between the degree of porosity, type of material processing and resulting mechanical properties for the use case of mesoporous aluminosilicate thin films that were co-assembled via a sacrificial block copolymer structure-directing agent. Several routes, including the introduction of chelating agents on the precursor solution, a two-step calcination process, and a variation over the aluminium content were explored with the objective of improving the scratch resistance and mechanical properties of the final mesoporous thin film. Pencil hardness tests were combined with atomic force microscopy analysis to investigate the macroscopic scratch resistance, i.e. plastic deformation. Ellipsometric porosimetry served to determine the elastic deformation of the nanoscopic architecture via measurement of the Young’s modulus. Our comparative investigation highlights the promising role of organic chelating agents to the sol-gel formulation to slow down the hydrolysis of the aluminium precursor, which facilitated improvements of the mechanical performance close to industrial standard.


Supplementary material

Supporting Information for manuscript "Enhanced Mechanical Stability and Scratch Resistance of Mesoporous Aluminosilicate Thin Films"
Document contains: - Figure S1. 2D GISAXS scattering patterns of the mesoporous aluminosilicate thin films with different porosity. - Figure S2. Pore size distribution obtained by EP for the different porosity samples studied. - Figure S3. Example images of pencil scratches using optical microscope. - Figure S4. Overview of optical and mechanical characteristics of reference coatings. - Table S1. Published pencil hardness values for mesoporous coatings. - Table S2. Published Young’s modulus values for mesoporous coatings. - Figure S5. Height profile from 2H pencil scratch. - Figure S6. Ellipsometric porosimetry ethanol absorption isotherms