Structure-director agent

This procedure is generally used to prepare zeolites. A gel is formed by hydro-thermal treatment (<200 °C) of an aqueous solution of NaOH, NaAl(OH)4, and Na2Si03 (a structure-director agent (SDA) can be added). Depending on the reactants nature and ratio, the SDA used, and the specific experimental conditions (temperature, pH, time, etc.), different structures can be formed. 

In the presence of minor amounts of Pr4N+, poorly crystalline ZSM-5 is obtained (6) while in complete absence of template, only limited amounts of ZSM-5 appear after several days of crystallization (7, 8). In that case, hydrated sodium ions constitute a poor replacement as template or pore filling agents for Pr4N+ (8). The crystallization rate of such systems can be considerably increased by addition of amines that then primarily act as pore fillers (5, 9, 10) but not necessarily as specific structure directors during nucleation (5). 

Structure directing agent, a blend of the BCP with chemical precursors of functional materials, rel3ung on microphase separation as an in situ structure director. 

This theory is based on the modernistic perspective and views an organization s optimal division structure, directors, boar members, production strategies, links to external organizations, etc. The main focus is on the acquisition of external resources and the consequences of this (Pfeffer Salancik 1978). The theory can be characterized as a modemistic-oriented (early) version of the agent theory. 

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