Andy Schoch PhD Candidate B.S. ChE, 2004, University of Illinois Urbana-Champaign Cook Hall 2053A, 1-5934 a-schoch at northwestern dot edu

Nanocomposite Gels 

The triblock copolymer PMMA-PnBA-PMMA in a selective solvent for PnBA exhibits a gelation transition. The transition is complex and the structure evolution is a function of concentration, temperature and time. A low viscosity liquid exists at high temperatures and low polymer concentrations and provides an ideal environment for dispersing carbon nanotubes. As temperature decreases in concentrated polymer solutions gelation occurs and an elastic solid forms. This happens because the PMMA endblocks are less soluble in the selective solvent and they form spherical micelles. The PnBA midblocks serve as tethers between each micelle throughout the gel structure. The carbon nanotubes become fixed in their positions once the gel forms and the composite properties can then be studied while the structure of the nanotubes are maintained.

These composite materials have been studied via rheological measurements, scanning electron microscopy after critical point drying, small and wide angle X-ray scattering, alternating current impedance spectroscopy, and after drying with dynamic mechanical analysis. All of this work has been co-advised by Professor Cate Brinson in the Mechanical Engineering Department here at Northwestern University.

SEM micrograph of dried MWNT/Polymer Composite

This work has been funded by the NSF through the NU-MRSEC grant.