Synthesis and physical characterization of arborescent (dendrigraft) polymers

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Our research efforts focus on the synthesis and the physical characterization of graft polymers with a dendritic architecture, the arborescent polymers (AP). These macromolecules have a uniform size ranging from 2-100 nm, very high molecular weights (1E4-1E8) and branching functionalities (f=10-10000+), and a controllable chemical composition. The extensive control achieved over the structure of these materials is highly beneficial, from a fundamental viewpoint, for the establishment of structure-property correlations in branched polymers, and for their utilization in nanotechnology-related applications. Five distinct activity areas have been identified in the current proposal: 1) The solution properties of AP with polyelectrolyte side chains will be examined, focusing particularly on the formation of gels in intermediate- to low-polarity solvents, as these materials may be useful as pH-sensitive smart gels. 2) Amphiphilic AP will be studied with respect to their ability to self-assemble, either at the air-water interface or in solution, to yield superstructures (e.g. rod-like and large compound micelle assemblies) and to pattern surfaces on the manometer scale. These copolymers will also be investigated for the solubilization and release of hydrophobic compounds in aqueous environments, to serve as model systems for the controlled delivery of hydrophobic drugs. 3) New AP with enhanced biocompatibility, potentially useful as practical drug delivery devices, will be synthesized from amino acids and investigated for their solubilization properties. 4) The rheological properties of AP incorporating elastomeric chain segments will be examined to improve the understanding of the influence of branching on polymer processability. 5) A new grafting technique using "click" chemistry will be developed to allow the high yield synthesis of AP with long side chains, which have been elusive so far. The fundamental knowledge gained from the proposed work will help clarify the influence of branching on different physical properties, over a much wider range of branching functionalities than has been achieved so far using other model systems such as the star-branched polymers.