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Glassy dynamics of poly(2-vinyl-pyridine) brushes with varying grafting densityElectronic supplementary information (ESI) available: See DOI: 10.1039/c5sm00213c

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 sil...

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Main Authors: Neubauer, Nils, Winkler, René, Tress, Martin, Uhlmann, Petra, Reiche, Martin, Kipnusu, Wycliffe Kiprop, Kremer, Friedrich
Format: Article
Language:English
Online Access:Get full text
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Summary: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. By using Broadband Dielectric Spectroscopy with nanostructured silicon electrodes we found that the segmental dynamics (dynamic glass transition) of a series of P2VP brushes is bulk-like.
ISSN:1744-683X
1744-6848
DOI:10.1039/c5sm00213c