Ordered Mesoporous Silicas and Carbons with Large Accessible Pores Templated from Amphiphilic Diblock Copolymer Poly(ethylene oxide)-<i>b</i>-polystyrene

Abstract

Highly ordered mesoporous carbons and silicas with ultralarge accessible pores have been successfully synthesized by using laboratory-made poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymers as templates via the evaporation-induced self-assembly (EISA) approach. Resols and tetraethyl orthosilicate (TEOS) serve as carbon and silica precursors, respectively. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements show that the mesoporous carbons (denoted as C-FDU-18) possess face centered cubic closed-packing (fcc) mesostructure (Fm3m) with large-domain ordering. N2 sorption isotherms reveal a large mesopore at the mean value of 22.6 nm with a narrow pore-size distribution. Mesoporous silicas (Si-FDU-18) also display a highly ordered fcc closed-packing mesostructure with an ultralarge unit cell (a = 54.6 nm). A hydrothermal recrystallization was introduced for the first time to produce micropores in thick silica walls (approximately 7.7 nm) and thus to generate ultralarge accessible mesopores (30.8 nm). Notably, the amphiphilic diblock copolymer with high molecular weight (PEO125-PS230, 29700 g mol-1) in this report was prepared via a simple method of atom transfer radical polymerization (ATRP). It can be easily available for chemists even without any experience in polymer synthesis.