Dresden 2017 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Polymer Networks and Dynamics II: Structure and Dynamics

CPP 22.3: Vortrag

Dienstag, 21. März 2017, 10:00–10:15, ZEU 250

Glassy dynamics in one- and two-dimensional nanometric confinement - a comparison — •Friedrich Kremer and Wycliffe K. Kipnusu — Institute of Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany

Glassy dynamics of polymers (e.g. poly(methylphenylsiloxane) (PMPS) or poly(cis1,4-isoprene) (PI)) is studied by broadband dielectric spectroscopy (BDS) in one-(1D)- and two-(2D)-dimensional nanometric confinement; the former is realized in thin layers having thicknesses down to 5 nm, the latter in unidirectional (length 50 m) nanopores with diameters varying between 4-8 nm. Based on dielectric measurements carried out in a broad spectral range at widely varying temperatures glassy dynamics is analyzed in detail in 1D and in 2D confinement. All the findings can be comprehended by considering the density of the polymer; in 1D it is assumed to be the same as in the bulk, hence the dynamic glass transition is not altered, in 2D it is reduced due to a frustration of packaging resulting in a higher free volume, as proven by ortho-positronium annihilation lifetime spectroscopy. [1] ``Dynamics in Geometrical Confinement'', F. Kremer (Ed.), Springer (2014) [2] Kipnusu, W.K. et al., ``Glassy dynamics of polymethylphenylsiloxane in one-and two-dimensional nanometric confinement-a comparison'', submitted 2016 [3] Kipnusu, W.K., ``Confinement for More Space: A Larger Free Volume and Enhanced Glassy Dynamics of 2-Ethyl-1-hexanol in Nanopores'' J. Phys. Chem. Lett. 6, 3708-3712 (2015) [4] Kipnusu, W.K., et al. ``Structure and Dynamics of Asymmetric Poly(styrene-b-1,4-isoprene) Diblock Copolymer under 1D and 2D Nanoconfinement'' ACS Appl. Mater. Interfaces, 7, 12328-12338 (2015) [5] Mapesa, E.U., et al. ``Molecular dynamics of poly(cis-1,4-isoprene) in 1- and 2-dimensional confinement'' in: ``Dynamics in Geometrical Confinement'', F. Kremer (Ed.), Springer (2014)