Using well-defined EO_nMA_m diblock amphiphilic copolymers as templates for synthesis of mesoporous silicas with different mesostructures

Highly ordered mesoporous silicas with large accessible pores have been prepared by using pre-synthesized poly(ethylene oxide)-b-poly(methyl acrlyate) (EO_nMA_m) diblock copolymers as templates. Via adjusting the chain length of EO versus that of MA, a series of silica mesostructures, including two-dimensional (2-D) hexagonal, 3-D bicontinuous (Ia3d), and body-centered cubic (Im3m) symmetries, were prepared with the use of tetraethyl-orthosilicate (TEOS) as the silica precursor under acidic conditions. The mesostructures of all materials were characterized by small-angle X-ray scattering and transmission electron microscopy measurements. N₂ adsorption-desorption isotherms reveal that the pore size ranges from 4 to 30 nm with a narrow pore-size distribution and its dimension is proportional to the chain length of MA units.