ZB 10 - Soft Condensed Matter (R. Holyst)

A depletion layer in polymer solutions at an interface oscillating at the subnano- to submicrometer scale

Author(s): Sozanski, Krzysztof and Wisniewska, Agnieszka and Piasecki, Tomasz and Karol and Ochab-Marcinek, Anna and Gotszalk, Teodor and Holyst, Robert
Title: A depletion layer in polymer solutions at an interface oscillating at the subnano- to submicrometer scale
Abstract: The mobility of segments of the polymer mesh in a solution determines dynamic response of the depletion layer (DL) to mechanical stimuli. phenomenon can be used to vastly decrease the local viscosity by any device performing periodic motion at the nano-and in complex liquids. We refined the vibrating quartz tuning (QTF) method to probe the viscosity of model aqueous solutions of glycol, covering a broad range of molecular weights (3 kDa 1 MDa) and QTF oscillation amplitudes (50 pm to 100 nm). For solutions of PEGs of high molecular weight, we found a drop local viscosity, up to two orders of magnitude below the bulk value. propose a simple explanation based on the motion of the depletion strongly supported by rheometry and dynamic light scattering We show that it is possible to directly probe the viscosity of DL and increase its thickness far above the equilibrium value. The role is played by the rate of relaxation of the entangled system. relevance of this paradigm ranges from the basic research on of entangled systems to design of energy-efficient nanomachines operating in a crowded environment.
Pages: 7762-7768
Journal: SOFT MATTER
Volume: 10
ID: ISI:000344998500012
Year: 2014
DOI: 10.1039/c4sm01280a