Self-Assembly in Poly(dimethylsiloxane)–Poly(ethyleneoxide) Block Copolymer Template Directed Synthesis of Linde Type AZeolite.

Wedescribe the hydrothermal synthesis of zeolite Linde type A(LTA) submicrometer particles using a water-soluble amphiphilic blockcopolymer of poly(dimethylsiloxane)-b-poly(ethyleneoxide) as a template. The formation and growth of the intermediateaggregates in the presence of the diblock copolymer have been monitoredby small-angle X-ray scattering (SAXS) above the critical micellarconcentration at a constant temperature of 45 °C. The early stageof the growth process was characterized by the incorporation of thezeolite LTA components into the surface of the block copolymer micellaraggregates with the formation of primary units of 4.8 nm with a core–shellmorphology. During this period, restricted to an initial time of 1–3h, the core–shell structure of the particles does not showsignificant changes, while a subsequent aggregation process amongthese primary units takes place. A shape transition of the SAXS profileat the late stage of the synthesis has been connected with an aggregationprocess among primary units that leads to the formation of large clusterswith fractal characteristics. The formation of large supramolecularassemblies was finally verified by scanning electron microscopy, whichevidenced the presenceof submicrometer aggregates with size ranging between 100 and 300nm, while X-ray diffraction confirmed the presence of crystallinezeolite LTA. The main finding of our results gives novel insight intothe mechanism of formation of organic–inorganic mesoporousmaterials based on the use of a soft interacting nanotemplate as wellas stimulates the investigation of alternative protocols for the synthesisof novel hybrid materials with new characteristics and properties. [ABSTRACT FROM AUTHOR]