Outreach in Charlottesville, VA David L. Green, University of Virginia Main Campus, DMR 0706373

1. Di-Block Copolymer Mediated Droplet AggregationDavid L. Green, University of Virginia Main Campus, DMR 0706373 We elucidate how diblock copolymers segregate to polymer droplet interfaces, mitigating coalescence and enhancing emulsification in polymer blends. Through formulation, we control the stretching of the copolymer at the droplet interface, and using in-situ optical rheology, we show that all copolymer-coated droplets aggregate when the copolymer saturates the surface (Fig. 1). We attribute droplet aggregation to the de-wetting, or the expulsion of the matrix upon copolymer saturation. We scaled the regions of droplet emulsification and aggregation by balancing the forces of shear with those due to the attraction between BCP-coated droplets (Fig 2). Ultimately, our work will impact the production of materials whose properties are optimized when the emulsified droplets are dispersed in the blend. Fig. 1. a) Droplets in 6 kg/mol PEP matrix with copolymer loading between bcp = 0 - 0.010. Droplet aggregation occurs at lower shear stress. Scale bars are 50 m; b) Phase diagram of scaled surface coverage with respect to scaled shear rate denoting regions of emulsification, coalescence, and aggregation.

2. Outreach in Charlottesville, VADavid L. Green, University of Virginia Main Campus, DMR 0706373 Prof. Green is active in student programs at the undergraduate and graduate level, teaching a core undergraduate class and a combined elective undergraduate and graduate class. Moreover, Dr. Green is an advisor for the 3rd year undergraduate students in the Department of Chemical Engineering (ChE). Throughout the duration of the grant, Prof. Green ran the Open House for the ChE at UVA in which we showed the results of our research to K-12 students along with their parents. Prof. Green made several presentations to his “Fundamental Surface Science” class, CHE 4442/6442 discussing the results of the research funded by the DMR Polymers grant. Lastly, Prof. Green routinely meets with elementary and middle school students from local Charlottesville City Schools to connect them to ongoing research in Chemical Engineering at UVA.