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|Author(s):||Brian C. Okerberg; H Marand; Jack F. Douglas;|
|Title:||Dendritic Crystallization in Thin Films of PEO/PMMA Blends: A Comparison to Crystallization of Small Molecule Liquids|
|Abstract:||Dendritic crystallization of PEO/PMMA thin films is reported. The film thickness is kept constant while the PMMA molar mass and blend composition are varied. Some basic features of dendritic growth, such as the diffusion length and tip curvature are discussed. The diffusion coefficient is tuned by varying the molar mass of the non-crystallizable PMMA and the blend composition. The observed dendrite tip radius is on the order of 50 nm and the shape of the growth envelope varies from square to needle-like as the PMMA molar mass or PMMA content is increased. The sidebranch spacing increases with the distance from the dendrite trunk with a power-law relationship that is also dependent on the PMMA molar mass and PMMA content. This coarsening process is similar to that reported for other classes of materials. The results of this study indicate that growth of polymer dendrites in thin film blends is controlled by processes similar to those reported in metals and small molecules.|
|Citation:||Plasma Processes and Polymers|
|Keywords:||blends,crystallization,dendrites,morphology,pattern formation,PEO,polymers,thin films|