Issue 42, 2011

Tunable hierarchical porosity from self-assembled chitin–silica nano-composites

Abstract

We studied new mesoporous materials with original properties and obtained from self-assembled chitinsilica nano-composites. Our novel synthesis allows the controlled colloidal assembly of α-chitin nanorods (bundles of elongated chitin monocrystals) and siloxane oligomers. Calcination of nano-composites results in mesoporous silica materials. Their pore volume fraction ϕPOR (0–0.52) is strongly correlated to the initial chitin content. Using N2 sorption and TEM data, we identify and characterize primary and secondary textural units related to the imprints of chitin monocrystals (2.5 nm wide) and nanorods (20–30 nm wide) respectively. Primary textural units are preserved over a wide ϕPOR range (linear relationship between pore volume and specific surface area). The coating of monocrystals by siloxane oligomers leads to a siloxane network of fractal nature as deduced from complementary SAXS data. Beyond a critical value ϕPOR′ estimated near 0.2, the coating is partial, and the porosity becomes more open and connected. At larger scales, the arrangements of secondary textural units result in complex textures and long-range ordering, showing similarities with textural features found in natural materials. We discuss the competition between entropy-driven transitions typical of anisotropic particles and kinetic arrest due to colloidal gelation and inorganic condensation. Finally, a schematic model for texture formation is given.

Graphical abstract: Tunable hierarchical porosity from self-assembled chitin–silica nano-composites

Supplementary files

Article information

Article type
Paper
Submitted
12 May 2011
Accepted
20 Jun 2011
First published
03 Aug 2011

J. Mater. Chem., 2011,21, 16997-17006

Tunable hierarchical porosity from self-assembled chitinsilica nano-composites

E. Belamie, M. Y. Boltoeva, K. Yang, T. Cacciaguerra and B. Alonso, J. Mater. Chem., 2011, 21, 16997 DOI: 10.1039/C1JM12110C

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