PMSE 38 |
| Crystallographic defects in polymer crystals can transport chains along their axis through a lamellar crystal of polyethylene and provide other responses to externally applied forces or electric fields. For example, the passage of a dispiration through a fold first raises the fold with respect to neighboring folds, as the dispiration enters, and then lowers the fold when the dispiration re-enters the crystal. The dispiration can be regarded as a self-assembled nanoscale machine, initiated by and interacting with external influences. The motion of such crystallographic defects can be influenced by external stress fields. In polyvinylidene fluoride, which has a dipole moment perpendicular to the chain, an external electric field can monitor or influence changes in the molecular conformation. Polymer crystals support a wealth of such kinematically defined nanoscale machines, which can be used to design systems that depend on nanoscale positioning of polymer molecules, using self assembled nanomachines. |
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50 Years after the Discovery of Polymer Single Crystals: A Look Back, Current Discoveries and Future Opportunities
8:30 AM-11:55 AM, Sunday, August 19, 2007 Westin Boston Waterfront -- Alcott, Oral
Division of Polymeric Materials: Science & Engineering |