TMOS/MTMS

Figure 1.13 Pseudomicellar aggregates form in the early stage of the polycondensation of TMOS-MTMS catalytic mixed gels in which lipophilic TPAP (in red) tends to concentrate in the cores of inaccessible cages. Because with time the material continues to evolve, these segregated TPAP molecules migrate and disperse in newly formed inner microporosity resulting in 10-fold improvement in catalytic activity. (Image courtesy of Massimo Carraro.)...

For example, increasing the hydrophobicity of the organosilica matrix drastically reduces the release rate as shown by Figure 18.6 profiling release for hydrophilic dyes entrapped in full microparticles. Clearly, with increasing amount of methyltrimethoxysilane (MTMS) in the TMOS/ MTMS precursor sol, the release rate drastically decreases. 

TAPOB was synthesized by reduction of l,3,5-tris(4-nitrophenoxy)benzene with palladium carbon and hydrazine in methanol [14], 6FDA was kindly supphed from Daikin Industries, Ltd. Pyromellitic dianhydride (PMDA) and 4,4 -oxidiphthahc anhydride (ODRA) were obtained from Daicel Chemical Industries, Ltd. and Manac Incorporated, respectively. TMOS, MTMS, 3-aminopropyltrimethoxysilane (APTrMOS), and N,N-dimethylacetamide (DMAc) were purchased from Aldrich. Chemical structures of monomers and alkoxysilanes are shown in Figure 8.2. 

The HBPI-silica hybrid membranes were prepared by thermal imidization and sol-gel reaction with two kinds of alkoxysilanes, TMOS and/or MTMS. Appropriate amounts of TMOS and/or MTMS and ion exchange water were added in the DMAc solution of the hyperbranched polyamic acids. For TMOS/MTMS combined system, TMOS and MTMS were added to achieve equivalent weight fraction of silica components arising from TMOS and MTMS. The mixed solutions were stirred for 24h and cast on PET films and... 

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