Regulation of Polymer Blend Morphology using Nanospheres and Nanorods

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TECHNICAL SUMMARY:The proposed research on "Regulation of Polymer Blend Morphology Using Nanospheres and Nanorods, "aims to understand how phase separation in polymer blendfilms affects the dispersion of nanoparticles (NP) and how NP affect phase evolution,wetting and film stability. Whereas prior studies focus on neat blends, the current studywill investigate how particle characteristics, in particular, surface chemistry and shape,influence how NP disperse and organize in a multi-phase morphology. Nanospheres ofsilica and nanorods of CdSe will be investigated. To control their location, NP arefunctionalized by acid-groups, neutral brushes, and attractive brushes. By tuning the surface properties, which control partitioning and organization, NP can be driven into onedomain or towards the interface between phases. The location of NP dictates filmcharacteristics including wetting layer growth rate, mprphology, phase evolution, andfilm stability. By controlling the location of NP, a new route for engineering phase size isexpected from these systematic studies. For example, stable biocontinuous structures canbe produced by NP "jamming" resulting in highly efficient photovoltaic devices. Theproposed research requires a palette of complementary depth and lateral profilingtechniques including ion beam etching combined with scanning electron microscopy.NON-TECHNICAL SUMMARY:Polymer nanocomposites (PNC) are foundin everyday materials such as tires andgolfballs as well as high technology devices for energy conversion and sensorapplications. PNC are examples of nano-based materials, which are driving therevolution in nanotechnology. This exploding field has received worldwide investmentstotaling $8 billion in 2004 with an anticipated impact of $2.6 trillion by 2014. Althoughhighly versatile and widely used, a fundamental understanding of PNC is lacking andbasic science is necessary to produce PNC based devises that are reliable, efficient andeconomical.During the past 3.5 years, this NSF project has provided research training for 25engineering undergraduates (10 females) and 6 high school teaching (2 female, 2minority). Two of these have received NSF Graduate Fellowships. Lectures aboutpolymer science to teachers in the Philadelphia School District has lead to greatenthusiasm about developing laboratories for a Science Van that will reach out to underrepresented nimorites in middle school. With University encouragement, the Science Van project is in the planning stages. International collaborations with scientistsfrom the United Kingdom and the Czech Republic will provide students with a betterunderstanding about research in these countries.