Crystallization of Small Organic Molecules in a Polymer Matrix: Multistep Mechanism Enables Structural Control.

The widely employed crystallization of organic molecules in solution is not well understood and is difficult to control. Employing polymers as crystallization media may allow enhanced control via temperature-induced regulation of polymer dynamics. Crystallization of a small organic molecule (perylene diimide) is investigated in polymer matrices (polystyrene) that enable the mechanistic study and control over order evolution.

Free-Standing Nanocrystalline Materials Assembled from Small Molecules.

We demonstrate a solution-based fabrication of centimeter-size free-standing films assembled from organic nanocrystals based on common organic dyes (perylene diimides, PDIs). These nanostructured films exhibit good mechanical stability, and thermal robustness superior to most plastics, retaining the crystalline microstructure and macroscopic shape upon heating up to 250-300 °C. The films show nonlinear optical response and can be used as ultrafiltration membranes.