| Abstract
| - Hydrophobic organosilicates with controlled morphologies at the nanometer length scalehave many potential applications in microelectronics and photonics. Here we report the useof block copolymers of poly(butadiene-b-ethylene oxide) (PB-b-PEO) as templates to create10−20-nm periodic hexagonal arrays of cylinders in hydrophobic organosilicates. The self-assembly process of the block copolymers is monitored and studied by solid-state NMR,transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). It is foundthat the microstructure and phase behavior of the nanocomposites are very sensitive to thepolymer−matrix interface and the intrinsic properties of the block copolymers. Whenmethyltriethoxysilane (MTES) is solely used as sol precursor to swell polymer domains, adisordered structure is always obtained, presumably because MTES changes its nature fromhydrophilic to increasingly hydrophobic during curing, and block copolymers are repelledfrom the matrix. A hydrophilic silicate precursor, (3-glycidyoxypropyl)-trimethoxysilane(GPTS), is introduced as an amphiphilic organosilicate precursor and to preserve thepolymer−silicate interface. A layered core-shell structure is formed with PEO and GPTSlocated at the interface, while PEO and GPTS are microphase separated. Understanding ofthe templating mechanism may provide a new route for nonlithographic nanopatterningand incorporating functionalities for photonic applications.
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