Templating of cylindrical and spherical block copolymer microdomains by layered silicates

The influence of a highly anisotropic layered silicate (organically modifie d montmorillonite) in directing the mesoscopic self-assembly of a block cop olymer blend is studied as a model for the development and tailoring of tem plated inorganic-organic hybrid materials. The potential for nanometer thic k layers to induce large-scale mesoscopic ordering of cylindrical and spher ical microdomains in asymmetric block copolymers is studied using a combina tion of rheology, electron microscopy, and small angle neutron scattering. Spherical microdomains arranged on a bcc lattice are templated by the aniso tropic layered silicate and the kinetics of their growth are dramatically a ccelerated by the presence of even 0.1 wt.% (0.04 vol.%) of the filler. How ever, for cylindrical microdomain ordering, the kinetics are essentially un affected by the addition of layered silicates and the development of three- dimensional mesoscopic order is possibly even disrupted. These results sugg est that for the development of three-dimensional well-ordered nanostructur es, the surface defining the pattern has to be significantly larger than th e leading dimension of the structure being templated. (C) 2001 American Ins titute of Physics.