Preparation of large-scale 2D zeolite crystal array structures to achieve optical functionality

We examined a method to refine a technique to prepare close-packed monolayers of cylindrical zeolite L crystals tethered on a substrate through covalent linkages, which was developed recently for popular use. We attempted to fabricate both vertical and horizontal-unidirectional alignments of the zeolite particles. The vertical alignment for centimeter scale large areas was achieved on a flat glass substrate by using flat-based zeolite crystals with an aspect ratio (length divided by width) of 1.1 while the crystals with an aspect ratio of 1.7 failed to align vertically. Thus the parameters important for successful alignment were determined. On the other hand, the unidirectional alignment in the horizontal packing structures was achieved by employing pregrooved substrates. We found that the relationship between the sizes of zeolite crystals and grooves is a crucial factor for the preparation of a close-packed structure. In this respect, our present preparation requires further improvements because it resulted in structures with many void spaces. Furthermore, we prepared the zeolite films loaded with unidirectionally aligned dyes to achieve optical functionalities.