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The role of block copolymers in industry continues to grow due to their intriguing and unique properties. In addition to linear and random copolymers, complex architectures show promise in the development of novel materials and in the understanding of macromolecular structures. Block copolymers often microphase separate into a variety of nano-scaled structures. The symmetry and defect density of these ordered domains play an important role in the macroscale optical and rheological properties of these materials. Furthermore, by carefully controlling the composition and molecular weight we can induce a transition from an ordered, periodic structure to a disordered non-spatially correlated structure using temperature. Unfortunately, in this temperature-induced disordered state copolymers are liquid-like, and therefore not robust for applications; however, we can improve the mechanical stability of the disorderd phase by crosslinking one of the blocks at a temperature above the order-disorder transition (ODT). Hence, we have experimentally shown that it is possible to obtain a polymer network that undergoes a reversible ODT, and thus we can create a robust soft solid that undergoes repeatable first-order bulk optical and mechanical transitions with a change in temperature. These materials are excellent candidates for nano-scaled optical switches and micro-fluidic valves. The self-assembly of amphiphilic block copolymers in dilute solution remains an unsolved problem. Our goal is to use molecular architecture to control the aggregation behavior and create well-defined structures in dilute solution. For example, by using block copolymers where one or more of the blocks are hydrophilic and the others hydrophobic we can mimic the locally planar structure of biological phospholipids in water. Therefore, our control over the architectural parameters (molecular weight, composition, symmetry, etc.) gives us the ability to better understand the role of competing effects due to the architecture of the individual amphiphilic molecules. To achieve these goals we perform depolarized light scattering, dynamic/static light scattering, X-ray scattering, light microscopy, transmission/scanning electron microscopy, rheometry, nuclear magnetic resonance, gel permeation chromatography and differential scanning calorimetry experiments. My areas of expertise lie in electron microscopy and light/X-ray scattering. 7. “Small-Angle Neutron Scattering Study of Structured Block Copolymer Gels” Durkee, D.A.; Gomez, E.D.; Ellsworth, M.W.; Bell, A.T.; Balasara, N.P. Submitted, 2007. 6. “Effect of Molecular Weight on the Mechanical and Electrical Properties of Block Copolymer Electrolytes”, Singh, M.; Odusanya, O.; Wilmes, G.M.; Eitouni, H.B.; Gomez, E.D.; Patel, A.J.; Chen, V.L.; Fragouli, P.; Iatrou, H.; Hadjichristidis, N.; Cookson, D.; Balsara, N.P. Macromolecules, in press, 2007. 5. “Zwitterionic Polymerization of Lactide to Cyclic Poly(Lactide) Using N-Heterocyclic Carbene Organocatalysts”, Culkin, D.A.; Jeong, W.; Csihony, S.; Gomez, E.D.; Balsara, N.P.; Hedrick, J.L.; Waymouth, R.M. Angewandte Chemie (Communication) 2007, 46, 2627-2630. 4. “Effect of Cross-linking on the Structure and Thermodynamics of Lamellar Block Copolymers”, Gomez, E. D.; Das, J.; Chakraborty, J. A.; Pople, J. A.; Balsara, N.P. Macromolecules 2006, 39, 4848-4859. 3. “Catalysts from Self-Assembled Organometallic Block Copolymers”, Durkee, D.A.; Eitouni, H.B.; Gomez, E.D.; Ellsworth, M.W.; Bell, A.T.; Balsara, N.P. Advanced Materials 2005, 17, 2003-2006. 2. “Platelet Self-Assembly of an Amphiphilic A-B-C-A Tetrablock Copolymer in Pure Water”, Gomez, E. D.; Rappl, T. J.; Agarwal, V.; Bose, A.; Schmutz, M.; Marques, C. M.; Balsara, N. P. Macromolecules (Communication) 2005, 38, 3567-3570. 1. “Signatures of the Order-Disorder Transition in Copolymers
with Quenched Sequence Disorder”, Eitouni, H. B.; Rappl, T.
J.; Gomez, E. D.; Balsara, N. P.; Qi, S.; Chakraborty, A. K.; Frechet,
J. M. J.; Pople, J. A. Macromolecules (Communication) 2004, 37, 8487-8490.
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