PMSE 415 |
| Inorganic-organic hybrid materials combine the functionality of an organic phase with the desirable properties of an inorganic phase, namely heat/chemical stability and enhanced modulus. Hybrid nanocomposites, in particular, are desirable due to interaction between the two phases at the nanometer scale, yielding superior properties over conventional composites (macro/micro scale). The research described herein presents the synthesis and characterization of a new amphiphilic nanocomposite system consisting of a single polyhedral oligosilsesquioxane (POSS), an eight membered silicon-oxygen cage, attached to one end of poly(ethylene oxide). These POSS-PEO hemitelechelics (HTs) differ in their pendant organic groups, cyclohexyl or isobutyl, located at the seven corners of each POSS cage. This small change leads to differences in thermal properties, both crystallization and ability to form micelles in water. The bulkier cyclohexyl version yielded less crystalline materials by hindering PEO packing and was also seen to have larger d-spacings between POSS cage aggregates, as shown by wide-angle x-ray diffraction. Only the isobutyl-POSS-PEO HTs formed micelles in water (diameter ~ 31 nm), again emphasizing that POSS pendant group composition is critical in determining cage aggregation. The observed micellear solutions are of interest because of their unusual geometry. In particular, hydrophobic POSS is large and spherical, in stark contrast with the typical hydrocarbon “tails” that normally form a micelle core. |
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Synthesis and Self-Assembly Approaches to Polymer-Inorganic Hybrid Nanoparticles
1:30 PM-4:10 PM, Wednesday, April 9, 2008 Hilton New Orleans Riverside -- Grand Salon 24, Oral
Division of Polymeric Materials: Science & Engineering |