Synthesis of hexagonal mesostructured aluminophosphate-based materials combined with organically bridged silsesquioxanes

Abstract

Hexagonal mesostructured aluminophosphate (AlPO)-based materials with organic groups embedded in the frameworks were prepared by using AlPO oligomers and organically bridged silsesquioxanes in the presence of hexadecyltrimethylammonium chloride (C₁₆TMACl). Ethylene bridged silsesquioxanes can be incorporated in the AlPO frameworks by using 1,2-bis(trimethoxysilyl)ethane (BTME). A small number of hexylene bridged silsesquioxanes were also incorporated in the AlPO-based frameworks by using 1,6-bis(trimethoxysilyl)hexane (BTMH). By increasing the added amount of BTMH, AlPO oligomers were covered with the hexylene bridged silicate species and disordered materials were formed. Ordered hexagonal mesostructured AlPO-based materials combined with BTME and BTMH can be successfully prepared by slightly changing the synthetic conditions. When these organically bridged silsesquioxanes were doped in the AlPO frameworks, the charge densities of the frameworks were reduced according to the presence of non-charged organic groups and therefore the surface curvature of C₁₆TMA assemblies increased, leading to the formation of hexagonal mesostructured materials. Moreover, a morphological variation such as the formation of macropores was found when hexagonal mesostructured AlPO-based materials were prepared in the presence of a large amount of BTME.