Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Interfaces and Thin Films II

CPP 18.7: Talk

Tuesday, March 23, 2010, 15:30–15:45, H39

Analysing the development of entanglements in spin coated films — •Julia Zabel and Alexander Blumen — Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg

As technological applications increasingly probe the nano scale and the importance of polymers in such devices rises, it becomes more and more important to understand the behavior of polymers confined to molecular lengthscales. Over the last years there has been a vast amount of experiments designed to understand the deviation of the properties of thin films from the bulk behavior. One can measure a film thickness dependence in such quantities as the glass transition temperature, the elastic modulus and relaxation times. But as varied as the experimental setups are the results. The often contradicting conclusions give rise to the suspicion that film preparation and annealing might play a large role in the outcome of the experiments. This is why we choose to research out-of-equilibrium films. In a toy model based on the spin coating process we simulate films of varying thickness and chain length. We then study their relaxation by analysing the polymers' conformation and entanglement over time. We discuss and compare different procedures to count entanglements, such as the determination of the self density, the so-called "packing model" and the Primitive Path Analysis. In this context we question whether reaching an equilibrium value for the polymer extension necessarily indicates that an equilibrium situation for the entanglements is reached.