|
چکیده
|
Mespoporous materials, also known as mesoporous molecular sieves, are a class of 3D-nanostructures with well-defined mesoscale (2–50 nm diameter) pores and surface areas up to 1000 m2/g.1 In terms of characteristic ordered feature size, they occupy a unique place between crystalline zeolites and other types of 3Dstructured materials described in this issue, e.g. 3DOM and direct-write materials with features > 100 nm. Mesoporous materials are formed by a self-assembly process from combined solutions of sol-gel precursors (e.g. metal alkoxides) and structure-directing amphiphiles, usually block-copolymers or surfactants (Figure 1).2,3Flexible, “one-pot synthesis” employing self-assembling templates enables the simultaneous control of size and 3D geometry (mesophase) of the pores. Furthermore, surface functionality of the pores can be modified by adding organically modified precursors, for example organosiloxanes RSi(OR’)3 or bis(organosiloxanes) (R’O)3Si- R-Si(OR’)3, to the initial reaction mix.4 On the other hand, it is relatively difficult to control long-range order and orientation of self-assembled structures and they typically have more defects and less structural precision compared to 3DOM or direct-write materials.
|