(439a) Engineering Interfaces and Functionality in Block Copolymer Self-Assembly
Diblock copolymers (A-block-B) spontaneously microphase separate and self-assemble into ordered lamellar, cylindrical, spherical, or network nanostructures with tunable dimensions from 5 to 100 nm. Such self-assembling materials are attractive for nanofabrication because the nanostructures 1) are spontaneously self-assembled in dense, periodic arrangements with length scales below those accessible to many conventional top-down fabrication processes, 2) have molecular-level control over the interfaces and surfaces, and 3) can be simultaneously generated over large areas. Nanostructures of diblock copolymers in thin films have therefore attracted significant excitement as a next-generation lithography technique.
In some instances, however, simple building blocks such as block copolymers self-assemble into structures that lack the complexity required for engineering applications. Here we will discuss some potential applications that benefit from additional control over the self-assembly process and approaches that are being used to engineer additional functionality into self-assembling materials. As one example, we will describe how control over the interface shape or profile of block copolymer structures in thin films may be achieved using multilayer assemblies of such materials. The resulting three-dimensional interface profiles are shown to improve processes for the transfer of block copolymer patterns into electronically functional metallic, semiconducting, or dielectric materials. Relevant to the area of block copolymer membranes, we will also present the impact of defects and defect engineering on the topology of block copolymer networks. By controlling the block copolymer structure through the choice of materials and processing conditions, it is demonstrated that the transport behavior through block copolymer networks or membranes may range from being percolating to completely non-percolating.