Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 29: POSTER: Polymer physics

CPP 29.41: Poster

Tuesday, March 8, 2005, 16:30–18:30, Poster TU D

Temperature dependent mechanical properties of polyelectrolyte shells — •Renate Müller, Nils Elsner, and Andreas Fery — Max Plank Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam

Polyelectrolyte multilayer capsules, that are produced by template assisted self assembly, are interesting either as biomimetic systems or for applications in encapsulation (drug delivery). In this context, the mechanical properties of the capsules are an important quantity, since they limit mechanical stability, behaviour in flow and adhesive properties. We have in the past established a combination of colloidal probe AFM technique as a force spectroscopy method and the RICM (reflectance interference contrast microscope) to directly investigate the compliance of individual microcapsules and derive elastic constants of the capsule wall material from the measurements. Here we focus on the effect of temperature on polyelectrolyte multilayer mechanics: Certain polyelectrolyte systems react towards temperature changes by shrinking and increasing their wall thickness. These changes are not reversible at return to room temperature. Thus capsules with varying wall thickness can be produced by different annealing times from the same starting batch in a simple manner. We can directly quantify how these shape changes are connected to changes in capsule compliance and additionally, we have investigated the dependency of the compliance on temperature by measurements during the annealing process.