Directed Assembly of Block Copolymer Templates for
the Fabrication of Mesoporous Silica Films with Controlled Architectures
via 3‑D Replication
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Abstract
Mesoporous silica films with cylindrical
or spherical pores up
to 40 nm in diameter were fabricated by replicating the morphologies
of polystyrene-<i>b</i>-poly(<i>tert</i>-butyl
acrylate), PS-<i>b</i>-PtBA, copolymers using CO<sub>2</sub>-assisted infusion and phase selective condensation of tetraethylorthosilicate
within the polymer template. The template structures, including domain
packing, orientation and spacing were controlled by adjusting the
molecular weight, volume fraction and polydispersities of the block
copolymers and by solvent annealing. Cylinder alignment was achieved
in polymer templates through directed self-assembly (DSA). The structural
details imparted to the template prior to precursor infusion were
retained in the mesoporous films. In one example, aligned PS-<i>b</i>-PtBA templates were replicated to yield massively parallel
arrays of cylindrical pores with pore diameters up to ∼20 nm.
The ability to tune pore sizes in this range within aligned nanochannels
is attractive for applications involving biomolecules