File Download

There are no files associated with this item.

  • Find it @ UNIST can give you direct access to the published full text of this article. (UNISTARs only)

Views & Downloads

Detailed Information

Cited time in webofscience Cited time in scopus
Metadata Downloads

How polymer surface diffusion depends on surface coverage

Author(s)
Zhao, JiangGranick, Steve
Issued Date
2007-02
DOI
10.1021/ma062104l
URI
https://scholarworks.unist.ac.kr/handle/201301/47320
Fulltext
https://pubs.acs.org/doi/10.1021/ma062104l
Citation
MACROMOLECULES, v.40, no.4, pp.1243 - 1247
Abstract
Measurements are presented of how surface diffusion of flexible polymers at the solid-liquid interface is controlled by surface coverage. Surface coverage is varied over the full range from dilute to saturated surface coverage. The method of measurement is fluorescence correlation spectroscopy (FCS), and the systems are poly(ethylene oxide) (PEG) and dextran adsorbed onto methyl-terminated self-assembled monolayers in buffered aqueous solution. A detailed study of PEG (M-w = 10 800 g mol(-1)) shows nonmonotonic behavior. The translational diffusion coefficient (D) at first increases with increasing surface concentration, presumably because the number of adsorption sites per molecule decreases as chains switch from pancake to loop-train-tail conformation. Excellent fits to behavior characteristic of a single diffusion process argue against aggregation or crystallization in the adsorbed state. In-situ ellipsometry measurements appear to rule out conformation changes to a hypothetical helical structure, as this would introduce birefringence to the adsorbed polymer layer causing deviations from the observed linear growth of apparent layer thickness with increasing surface coverage. For all three samples studied (PEG of M-w = 10 800 and 20 000 g mol(-1) and also dextran with M-w = 10 000 g mol(-1)), D at surface coverages larger than the estimated surface overlap concentration slow by 1 order of magnitude, presumably reflecting crowding and entanglement with neighboring chains.
Publisher
AMER CHEMICAL SOC
ISSN
0024-9297
Keyword
FLUORESCENCE CORRELATION SPECTROSCOPYADSORBED POLYMER2 DIMENSIONSEQUILIBRIUMMONOLAYERSMOLECULESMICADNA

qrcode

Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.