POLYMER NANOENCAPSULATED ACID-CATALYZED SOL-GEL SILICA MONOLITHS

摘要

Macroporous monolithic silica aerogels having mesoporous walls are produced via an acid- catalyzed sol-gel process from tetramethoxysilane (TMOS) using a triblock co-polymer (Pluronic P123) as a structure-directing agent and 1,3,5-trimethylbezene (TMB) as a micelle- swelling reagent. Pluronic P 123 was removed by solvent extraction, and monoliths were obtained by removing the pore-filling solvent with liquid CO2, which was removed under supercritical conditions. The resulting materials are more robust compared to base-catalyzed silica aerogels of similar density. Mechanical properties can be further improved by reacting a di-isocyanate with the silanol groups on the macro and mesoporous surfaces. The polymer forms a conformal coat on the macropores and blocks access to the mesopores of templated samples, so that BET surface areas decrease dramatically.