Directed assembly of cylinder-forming block copolymers into patterned structures to fabricate arrays of spherical domains and nanoparticles

The first demonstration of the directed assembly of cylindrical microdomains of a block copolymer into nonregular, patterned structures, as well as the subsequent formation of registered 1D arrays of spherical microdomains and nanoparticles, is presented. Directed assembly of pure cylinder-forming polystyrene-block-poly(t-butylacrylate) copolymer, which can undergo a cylinder-to-sphere morphological transition via thermolysis, on lithographically defined linear, circular, or angled chemical nanopatterns resulted in long-range-ordered cylindrical domains that were registered to the underlying nanopattern. Thermolysis of the cylindrical domains yields registered arrays of spherical domains, which are difficult to pattern with advanced lithographic techniques. The spherical domains maintain uniform size in all patterns studied, including 45 degrees corners. In situ synthesis of metal and metal oxide nanoparticles within the spherical microdomains created linear, circular, and angled nanoparticle 1D arrays, registered to the chemical nanopattern. The nanoparticles within the 1D arrays were spaced uniformly, and the distance between arrays could be controlled independently of the particle size and interparticle spacing. The combined technique provides a hierarchical route for the fabrication of long-range-ordered 1D metal and metal oxide nanoparticle arrays.