Nanoblock Aggregation-Disaggregation of Zeolite Nanoparticles: Temperature Control on Crystallinity

During the induction period of silicalite 1 formation at 80 degrees C primary nanoblocks of 8-11 nm self-assemble together into fragile nanoflocculates of ca. 60 nm that dislocate and reappear according to a slow pseudoperiodical process. Between 22 and 32 h, the nanoflocculates grow up to 350 nm and contain ill- and well-oriented aggregates of ca. 40 nm. After 48 h only ill-faceted monodomains of ca. 90 nm remains, which self-assemble into larger flocculates of ca. 450 nm. For crystal growth performed at 90 degrees C most of the final aggregates exhibit ill-oriented assembly. This is consistent with a trial-and-error block-by-block building mechanism that turns into an irreversible and apparently faster process at 90 degrees C, causing definitely ill-diluted and ultrasonicated solutions, using mainly dynamic light scattering and cryo-high-resolution transmission electron microscopy at various tilted angles.