Dr. Monica H. Lamm
Department of Chemical and Biological Engineering
Iowa State University
Ames, IA 50011
Molecular Simulations of Soft Materials
Monday, September 15, 2008
New developments in synthetic and materials chemistry continue to produce a wide variety of building blocks for advanced materials that possess novel structure and function. This talk will describe our recent work aimed at connecting the molecular-level properties of nanoscale building blocks to the macroscopic properties of materials. In one example, we will show how triblock copolymers, designed to have specific affinity for nanoparticles at the chain ends, provide a robust strategy for organizing nanoparticles. We will present a detailed investigation of triblock copolymer mediated assembly as a function of both nanoparticle size and concentration. Next to phases such as hexagons or gyroids, regularly observed in copolymer solutions and melts, we find a novel square columnar phase of two interpenetrating line-lattices of micellar cylinders and aligned nanoparticles. We argue that this phase is a realization of the packing problem of binary mixtures of disks. Our study suggests that nanoparticle assembly with functionalized block copolymers can provide a simple and efficient tool for assembling novel materials with nanometer scale resolution. Other examples to be covered include the self-assembly of linear-dendritic block copolymers and the diffusivity of fractal aggregates.