Novel Self-Assembled Nanostructures from Well-defined Amphiphilic Block Copolymers

K. Hong, J. W. Mays, and P. F. Britt, CNMS Macromolecular Complex System Group

Self-assembly is the autonomous organization of components into patterns or structures. Self-assembling processes are common throughout nature and technology. They involve components from the molecular (~10-9m) to the planetary (~106m) scale and many different kinds of interactions. Self-assembly is of interest to many within the greater scientific community because it is a ubiquitous phenomenon in living organisms which provides numerous examples of functional ensembles which stimulate the design of nanostructures with desired functions and properties. One of the greatest challenges to researchers in the materials sciences is the design and synthesis of materials with exact structures and specific functions as a result of self-assembling. The self-assembling of synthetic block copolymers provides a very promising route to achieve this goal.

The structures from self-assembled amphiphilic block copolymers in solution are influenced by many parameters including composition and molecular weight of the block copolymers. Perhaps the most important parameters are the inherent characteristics of the polymer itself. We recently discovered that a highly ordered pyramid nanostructure formed in polystyrene-block-sulfonated poly(1,3-cyclohexadiene) (PS-b-sPCHD) block copolymer in acidic solutions. It is the first time that such highly ordered nano-pyramids formed in polymer solutions. We believe that hydrogen-bonding and the intrinsic structure characteristics of the PCHD block (rigidity) play the central role in the self-assembling process. The size of the unique nanostructures can be tuned by changing the composition and/or molecular weight of this particular polymer system. These nanostructures will find potential applications in many areas such as photonics, optoelectronics, and thermal electronics.

This work was carried out within Partner User Proposal CNMS2003-041, including contributions from researchers sponsored by the BES Division of Scientific User facilities. Partner users (PI J. M. Simonson) were supported by the BES Division of Chemical Sciences, Geosciences and Biosciences under FWP ERKCC49.