Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster: Crystallisation, Nucleation and Self assembly

CPP 17.10: Poster

Dienstag, 27. März 2012, 18:15–20:15, Poster A

Polymer induced changes of the crystallization scenario in suspensions of hard sphere like microgels — Richard Beyer, Sara Iacopini, Thomas Palberg, and •Hans-Joachim Schöpe — Institut für Physik, Johannes Gutenberg Universität, Mainz, Germany

We investigated the crystallization scenario of hard sphere like Polystyrene microgels suspended in the good solvent 2-Ethylnaphtalene using time resolved Bragg scattering. The slightly polydisperse samples were prepared at the melting volume fraction of the polymer free system around 0.55. For the polymer free samples we obtained polycrystalline solids via the two-step crystallization scenario known from hard sphere suspensions with little competition of wall crystal formation. Addition of non-adsorbing low molecular weight Polystyrene polymer leads to a considerably slowed crystal growth. Further we observed a delay of precursor to crystal conversion for the bulk particles while the induction times for wall nucleation are reduced. The increased polymer concentration thus shifts the balance between the two crystallization pathways and the relative amount of wall based crystals can be tuned.