This ICC proposal by Professor Edward Bryan Coughlin of the University of Massachusetts, Amherst, will be supported by the Dynamics group within the Organic and Macromolecular Program in the Chemistry Division of MPS. The German collborators are Dr. Patrick Theato, Institute for Organic Chemistry, and Professor Jochen S. Guttmann, Instutute for Physical Chemistry, Johannes Gutenberg University, Mainz. They will be supported by the Deutsche Forschungs Gesellshaft (DFG). Block copolymers, two chemically different polymers joined together at one end, separate into arrays of domains comparable to the dimensions of the polymer chains (approximately on the 10 nanometer length scale). The generation of nanoporous materials from ordered block copolymers relies on a selective removal of one block without compromising the integrity of the matrix material. By use of a photocleavable unit at the junction point of a block copolymer, the removal of one of the components will not depend on the chemical nature of the minor component and thus will be applicable to a much larger variety of block copolymers. Cleavage of the junction point upon photolysis, followed by removal of the minor components via selective solvent extraction, is thus a promising strategy for preparation of the next generation of nanoporous structures from block copolymers. In this proposal the PIs will develop synthetic methodologies to incorporate o-nitrobenzyl esters or phenacyl esters as photocleavable junctions in block copolymers. These materials will be prepared using a combination of organic synthesis and then controlled radical polymerizations. The PIs will systematically explore photolysis conditions that will lead to rapid, clean and efficient photocleavage in the solution state. With this knowledge base they will then study cylindrically or perforated lamellar microphase separated morphologies in thin films and in the bulk. Photocleavage and removal of the minor component by selective solvent extraction will thus yield novel nanoporous templates. The knowledge gained in how to generate nanoporous templates or scaffolds will have future applications in a number of different scientific fields. The development of a range of novel block copolymers will also allow them to probe a broad scope of fundamental polymer physical chemistry investigations involving polymer chain diffusion dynamics from rapidly created meta-stable states. This will provide the possibility to investigate the transformation from a defined micro-phase separated block copolymer morphology to a macroscopic separation of two immiscible homopolymers depending on the previously inscribed morphology. This International Collaboration in Chemistry proposal will allow United States graduate students to perform critical portions of their doctoral research in Germany. The research collaboration coupled with the international exchange of students will create a future US workforce of scientists and engineers that are globally-engaged, scientifically as well as culturally and socially.
