Synthesis of hierarchically structured silica with polypeptide-based triblock copolymer as a template

Hierarchically structured silica was synthesized at near-neutral pH and under ambient conditions, utilizing synthetic polypeptide-based triblock copolymer poly(l-phenylalanine)-b-poly(ethylene glycol)-b-poly(l-phenylalanine) (Phe7–PEG135–Phe7) as a template. In the synthesis procedure, anilino-methyl triethoxy silane (AMTS) was used as an intermedium, i.e., on one hand it interacts with polypeptide-based triblock copolymer through π–π interaction between the phenyl groups of Phe segments and AMTS; on the other hand, AMTS can co-condense with tetraethoxylsilane (TEOS) through hydrolysis process. The prepared silica possesses mesoscale short-range-order and exhibits hierarchical structure with both supermicropores and interconnected layers of macropores. It is proposed that the supermicropores are templated by the polypeptide segments, while the open 3D interconnected macroporous networks are presumably ascribed to both PEG segments and organic solvent. It is proved that both polypeptide-based block copolymer and AMTS play important roles in the formation of mesoscale short-range-order and hierarchical structure.