The design and synthesis of polymers with controlled architecture and functionality that can perform catalytic functions or act as transport channels is undertaken. The overall design of the macromolecules requires that fine control over both architecture and the placement of functional groups within the active macromolecules be achieved. For transport channels, dendronized macromolecules that possess a tubular shape are expected to be most appropriate in analogy to biological channels that result from the self assembly of several proteins. For catalysis, globular macromolecules based on a star architecture enable the incorporation of a catalytic core while the arms of the star may provide for site isolation in analogy with the site isolated core of catalytic enzymes. This program exploring new ways to obtain functional macromolecules with persistent structural features will make use of all the tools of modern synthetic polymer chemistry while also developing new reactions, methods of assembly, and methods of characterization. Applications of the macromolecules in catalytic processes, the sequestration or the transport of materials will also be explored in proof-of-concept studies.
NON-TECHNICAL SUMMARY This project is directed towards the design of novel polymeric materials that can help meet the needs of society in areas as varied as the manufacturing of novel substances, water purification, or the removal of pollutants from waste streams. Both the shape and the function of the new polymeric materials draw some inspiration from natural biological systems, for example imitating natural enzymes in the way they facilitate chemical transformations, or mimicking the natural channels that selectively transport fluids or ions in and out of cells in the human body. The project will train young scientists at the state of the art in polymer science, a field of immense impact in our daily lives through new and unique materials as varied as specialty plastics, electronic and energy materials, or therapeutic and diagnostics agents.
The target of this work was the creation of fully synthetic macromolecules that mimic the function of enzymes. Such artificial molecules would be able to carry out chemical reactions while avoiding or reducing the use of harsh chemicals or environmentally unsound processes. Synthetic polymers containing a catalytic cavity engineered to be the site where chemical reactions would occur have been designed. However, unlike enzymes, which are able to maintain a specific shape surrounding a catalytic cavity, most synthetic polymers are highly flexible and do not have any shape persistence. Therefore, we have chosen to work with specially designed polymers that are highly branched – dendrimers or star polymers - such that their branches effectively encapsulate the central portion or "core" of the macromolecule. The dendrimers or star polymers we have developed are a few nanometers in size, with numerous arms surrounding this core where the catalytic site will be located. Thus, the arms can be used to both provide protection for the core avoiding its deactivation, while also assisting with the shuttling of reactive molecules back and forth from surrounding medium to the catalytic core where the reactions take place. Significant success was demonstrated using this approach and several synthetic enzyme-like catalysts were demonstrated while a general route to their production was also developed. However, the project had to be discontinued in 2011, much before the end of the grant period and before significant findings could be confirmed and published due to early termination of the grant following the relocation of the PI at a new Institution.