POLY 246 |
| The use of synthetic polymerization techniques (e.g., controlled radical polymerizations) that often yield polydispersity indices greater than 1.1 is becoming more widespread. Advances in these methodologies have increased the number of monomers that can be readily incorporated into block copolymers and have the potential to drive commercial costs down. Since many block copolymer properties are governed by the underlying polymer microstructure, understanding the influence of polydispersity on morphological behavior could prove vital to the success of block copolymer commercialization efforts. This presentation will focus on polydispersity-driven morphological transitions in poly(isoprene-b-styrene-b-ethylene oxide) (ISO) triblock terpolymers. ISO triblocks with polydisperse (Mw/Mn = 1.31, 1.44) polystyrene blocks were prepared by anionic polymerization using the functional organolithium 3-triisopropylsilyloxy-1-propyllithium. The morphological behavior of these polydisperse ISO triblocks was characterized using small-angle x-ray scattering and dynamic mechanical spectroscopy. Only lamellar microstructures were identified along the fI = fS isopleth for polydisperse ISO triblocks, whereas an orthorhombic network phase (O70) was previously identified in monodisperse ISO triblocks. These results are the first reported investigation of the effects of varying polydispersity of the B block in ABC triblock terpolymers. |
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Excellence in Graduate Polymer Science Research
8:25 AM-11:40 AM, Monday, April 7, 2008 Hilton New Orleans Riverside -- Grand Salon 18, Oral
Division of Polymer Chemistry |