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Authors Neubauer, N. ; Winkler, R. ; Tress, M. ; Uhlmann, P. ; Reiche, M. ; Kiprop Kipnusu, W. ; Kremer, F.
Title Glassy dynamics of poly(2-vinyl-pyridine) brushes with varying grafting density
Date 17.03.2015
Number 45483
Abstract The molecular dynamics of poly(2-vinyl-pyridine) (P2VP) brushes is measured by Broadband Dielectric Spectroscopy (BDS) in a wide temperature (250 K to 440 K) and broad spectral (0.1 Hz to 1 MHz) range. This is realized using nanostructured, highly conductive silicon electrodes being separated by silica spacers as small as 35 nm. A “grafting-to”-method is applied to prepare the P2VP-brushes with five different grafting densities (0.030 nm-2 to 0.117 nm-2), covering the “true-brush” regime with highly stretched coils and the “mushroom-to-brush” transition regime. The film thickness ranges between 1.8 to 7.1 (±0.2) nm. Two relaxations are observed, an Arrhenius-like process being attributed to fluctuations in the poly(glycidyl-methacrylate) (PGMA) linker used for the grafting reaction and the segmental dynamics (dynamic glass transition) of the P2VP brushes. The latter is characterized by a Vogel–Fulcher–Tammann dependence similar to bulk P2VP. The results can be comprehended considering the length scale on which the dynamic glass transition (=1 nm) takes place.
Publisher Soft Matter
Wikidata 6
Citation Soft Matter 11 (2015) 3062-3066
DOI https://doi.org/10.1039/C5SM00213C
Tags responsive polymer brushes polystyrene thin-films holes diffusion-model t-g poly(methyl methacrylate) molecular-motion layers transition interface spectroscopy

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