Preparation of mesostructured silica–micelle hybrids and their conversion to mesoporous silica modified controllably with immobilized hydrophobic blocks by using triethoxysilyl-terminated PEO–PPO–PEO triblock copolymer

Abstract

Mesostructured silica having mesopore surface functionalized with poly(ethylene oxide)₂₀-b-poly(propylene oxide)₇₀-b-poly(ethylene oxide)₂₀ (EO₂₀PO₇₀EO₂₀, P123) micelles was synthesized by using triethoxysilyl-terminated P123 (TES-P123) with dual functions of templating and surface anchoring. The amount of anchored P123 was controlled by mixing TES-P123 and conventional P123 as a cotemplate and the subsequent removal of the cotemplate by extraction. All the samples show the presence of ordered mesopores after the extraction. Unexpectedly, the d-spacing and the pore size increased after the extraction when the ratio of TES-P123/(TES-P123 + P123) was over 75%, which is explained by an osmotic force caused by anchored P123 swollen with THF during the extraction. To evaluate the stability of anchored P123, ibuprofen was simultaneously incorporated into mesopores during the formation of mesostructured silica. When TES-P123 was exclusively used, the percentage of retained P123 after the extraction of IBU was higher than that found for the case of conventional P123. This approach will open a new way to stabilize assembled amphiphiles in regularly ordered siloxane frameworks.