Templating behavior of a triblock copolymer surfactant with very long hydrophilic PEO chains (PEO_(140)PPO_(39)PEO_(140)) for the synthesis of cubic mesoporous silica with large cage-like cavities

摘要

A series of cubic mesoporous silica materials exhibiting large cage-like cavities (up to 12.5 nm) interconnected through windows (Im3m symmetry group) and with a mesopore volume as high as 1.30 cm~3 g~(-1) have been synthesized for the first time by using a new polyalkylene oxide-based triblock copolymer (PEO_(140)PPO_(39)PEO_(140)). The ability of this new triblock copolymer surfactant to act as a template for well-defined multidirectional pore network cubic silica particles, exhibiting tailored porous characteristics, was shown to depend on the synthesis conditions, in particular the acidity and temperature, as well as the presence of a cationic co-surfactant. These parameters influence the aggregation of nanoparticles either in micron-sized particles with different nanoparticles coalescence degrees or in blocks of aggregated nanoparticles. The aforementioned materials were characterized by small angle X-ray powder diffraction, nitrogen adsorption, scanning and transmission electronic microscopy, while the hydrodynamic diameters of the new triblock copolymer species were determined in situ by dynamic light scattering.