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The microstructure of anisotropically shaped grains can strongly influence a range of material properties, including transport, mechanical and electro-optical. A grain-structure-related phenomenon, known as excluded volume epitaxy (EVE), is reported in this study. EVE is a local, inter-grain orientational correlations effect, which results from a combination of continuous nucleation of anisotropic grains and impingement of growing grains. Due to EVE, anisotropically shaped grains have a tendency to be similarly aligned in a local neighbourhood, despite the absence of any forced global orientation in the sample. The effect has been repeatedly observed by the authors in block copolymers, as illustrated by a representative TEM image. Optical microscopy of anisotropically shaped non-polymeric crystals revealed the generality of this effect. The simulation study revealed a tendency for azimuthal, inter-grain orientational correlation and re-confirmed the experimental observation of EVE.

The tensile properties of tetra-functional multigraft copolymers have been shown to have surprising high strain at break (~2100%), about double that of commercial thermoplastic elastomers such as Kraton! Currently, multigraft copolymers can be synthesized with a variety of branches (single, bi, tri-, tetra, and with different lengths) at each branch point and there can be a large number of branch points per molecule that are regularly, randomly, or heterogeneously spaced, each of which can have effects on mechanical properties. Unfortunately experimental synthesis and characterization of these novel polymer systems is quite time consuming. This is where molecular modeling and simulation can be critical for mapping out the fundamental mechanisms responsible for the observed behavior and to optimize/focus the experimental efforts. In this article we report details of our experimental synthetic and characterization effort along with some preliminary results from molecular dynamics, molecular mechanics, Monte...

This work examines the flow of foams through porous materials by characterizing the foam bubble sizes before and after injection through a porous medium. Foam cell sizes are measured using an image analysis system and software developed in our laboratory. Glass mats are used as the porous medium, and foam is forced to flow through a mat at a specified porosity under a constant driving pressure. Results indicated that the size of the bubbles exiting the porous mat was independent of the bubble size of the foam entering the mat and dependent on the average pore size of the medium. Results are also presented which demonstrate the effect of foam quality on the bubble size.