Surfactant-mediated self-assembly of nanocrystals to form hierarchically structured zeolite thin films with controlled crystal orientation

Abstract

We report on a scalable wet deposition to simultaneously manipulate the self-assembly and orientation of zeolite Linde Type A (LTA) nanocrystals. This process, referred to as surfactant-mediated self-assembly (SMSA), creates zeolite LTA thin films with long-range ordered cylindrical patterns, wherein {100} faces of the crystals are preferably oriented parallel to the support surface. This approach makes it possible to control the diameter as well as the depth of the cylindrical patterns in zeolite thin films fabricated via scalable wet deposition. To elucidate the mechanism underlying the SMSA process, we applied in situ imaging to cast solutions subjected to a temperature swing. Our results indicate that the cylindrical patterns may be developed from micelles of the surfactant, which make up a thermodynamic phase in the cast solution. We also demonstrate that the apparent dielectric constant and optical haze of the zeolite LTA thin films can be engineered by altering the dimensions of the cylindrical patterns.