Macromolecular Engineering by Controlled/Living Radical Polymerization

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TECHNICAL SUMMARYControlled/Living Radical Polymerization (CRP) is among the most rapidly developing areas of chemistry. CRP is a powerful synthetic technique for preparation of many well-defined macromolecular structures and can be used to produce new specialty materials. The main objective of this proposal is to explore the effect of several molecular structural parameters on the morphology and properties of a range of new materials that were specifically designed, prepared and characterized to expand the knowledge of how the properties of material develop. The main intellectual challenge is to precisely control the molecular structure and also to determine how imperfections in chain uniformity, composition or topology will affect some macroscopic properties. Two or more incompatible monomers will be copolymerized in statistical, gradient, multisegmented and blocky ways; the resulting copolymers will be characterized; their morphology as well as their thermomechanical and other physical properties will be studied. Monomers which yield amorphous polymers with high and low glass transition temperature but also monomers which can crystallize and those which will form amphiphilic systems will be used. The effect of branching and the effect of the number of arms in star-block copolymers on the properties of a spectrum of copolymers will be cdetermined. New miktoarm star polymers will be prepared and analyzed in detail how variations in the synthetic procedure can affect their structure and some of their properties. (Co)polymers which exhibit lower critical solution temperature (LCST) will be synthesized and the effect of sequence distribution of monomers in the copolymer and molecular architecture on LCST behavior will be studied. The degradation rate of model polymers, with various degradable linkers, will be evaluated and a correlation between their structure and pH dependent degradation rate will be devloped. These degradable units will be incorporated into polymer segments in a controlled fashion to prepare degradable vinyl polymers. NON-TECHNICAL SUMMARYThe results from this proposal will generate broader impact by educating graduate, undergraduate students and postdoctoral fellows, by dissemination information generated in this project via timely publications (including "J. Chem. Ed."), internet and presentations at (inter)national symposia and CMU outreach programs. CRP Consortium with ~ 10 companies which benefit from all knowledge generated by NSF supported activities will be continued. The impact of the proposed research will extend beyond synthetic polymer chemistry. It could affect basic concepts in materials science and lead to the development of some commercially valuable materials.