Block copolymers are hybrid macromolecules that contain multiple, covalently connected polymer segments. These materials self-assemble on nanometer length scales and can adopt a variety of ordered morphologies. For AB diblock copolymers, hexagonally packed, nanoscopic cylinders of the A component in a matrix of the B component is a commonly observed morphology. For ABC triblock terpolymers, a morphology with cylinders of the A component, surrounded by a shell of the B component, in a matrix of the C component is prevalent. Selective chemical etching of the A component in both of the cases will lead to nanoporous materials with channels templated by the sacrificial component. This approach to the synthesis of nanoporous materials using aliphatic polyesters and polyethers as the degradable components is central to this project. Methods aimed at enhancing the mechanical integrity of nanoporous materials from ordered block copolymers will be explored. These include the design and development of matrix polymers that are either highly entangled, semi-crystalline, or thermoplastic elastomers. These efforts will significantly expand understanding of mechanical properties in nanoporous plastics and provide the basis for future applications of these materials. In addition, the use of block copolymer-derived nanoporous materials as high surface area supports for heterogeneous catalysis will be examined. The tunable nature of these substrates is particularly noteworthy and will enable both a detailed understanding of how these materials behave as media for supported catalysts and development of these materials as practical catalyst supports. Supported versions of nanoparticles, simple organocatalysts and more complex peptide based catalysis, and enzymes will be explored for a variety of catalytic and asymmetric transformations.
NON-TECHNICAL SUMMARY: Porous materials have found utility in an extremely wide range of technological applications. These ubiquitous organic and inorganic materials are commercially important as, for example, catalysts in the petrochemical industry, separation media for biotechnology, and interlayer dielectrics for microelectronics. The principal objective of this work is to design, synthesize and develop new classes of polymeric (i.e., plastic) nanoporous materials (porous materials with nanometer sized pores) with wide-ranging, tunable properties. This work is motivated by advanced nanotechnological applications and will focus on uncovering fundamental principles associated with the synthesis and ultimate tuning of the chemical and physical properties of these novel materials. Materials developed in this proposal will ultimately lead to societal benefit through applications in separations (e.g., water purification) and catalysis (i.e., Green Chemistry). The use of nanoporous materials for these purposes has been reported, and this research will directly impact the utility of block copolymers in these applications. Broad polymer science training of the researchers working on this project will also result, and specific strategies aimed at communicating the importance of basic research to both undergraduate students and the public will be implemented.
