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Title: Measuring the structure of thin soft matter films under confinement: A surface-force type apparatus for neutron reflection, based on a flexible membrane approach

Abstract

A unique surface force type apparatus that allows the investigation of a confined thin film using neutron reflection is described. The central feature of the setup consists of a solid substrate (silicon) and a flexible polymer membrane (Melinex{sup Registered-Sign }). We show that inflation of the membrane against the solid surface provides close and even contact between the interfaces over a large surface area. Both heavy water and air can be completely squeezed out from between the flexible film and the solid substrate, leaving them in molecular contact. The strength of confinement is controlled by the pressure used to inflate the membrane. Dust provides a small problem for this approach as it can get trapped between membrane and substrate to prevent a small part of the membrane from making good contact with the substrate. This results in the measured neutron reflectivity containing a small component of an unwanted reflection, between 10% and 20% at low confining pressures (1 bar) and between 1% and 5% at high confining pressures (5 bar). However, we show that this extra signal does not prevent good and clear information on the structure of thin films being extracted from the neutron reflectivity. The effects of confinementmore » are illustrated with data from a poly(vinyl pyrollidone) gel layer in water, a polyelectrolyte multilayer in water, and with data from a stack of supported lipid-bilayers swollen with D{sub 2}O vapor. The data demonstrates the potential of this apparatus to provide information on the structure of thin films under confinement for a known confining pressure.« less

Authors:
 [1];  [2]; ;  [3]; ;  [1];  [4]
  1. School of Chemistry, University of Bristol, Cantock's close, BS8 1TS Bristol (United Kingdom)
  2. (United Kingdom)
  3. School of Physics, University of Bristol, Tyndall Avenue, BS8 1TL Bristol (United Kingdom)
  4. ISIS Neutron Source, STFC Rutherford Appleton Laboratory, OX11 0QX Didcot (United Kingdom)
Publication Date:
OSTI Identifier:
22093989
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 83; Journal Issue: 11; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; HEAVY WATER; INTERFACES; LAYERS; NEUTRONS; POLYMERS; REFLECTION; REFLECTIVITY; SILICON; SOLIDS; SUBSTRATES; SURFACE FORCES; SURFACES; THIN FILMS

Citation Formats

Vos, Wiebe M. de, School of Physics, University of Bristol, Tyndall Avenue, BS8 1TL Bristol, Mears, Laura L. E., Richardson, Robert M., Cosgrove, Terence, Prescott, Stuart W., and Dalgliesh, Robert M. Measuring the structure of thin soft matter films under confinement: A surface-force type apparatus for neutron reflection, based on a flexible membrane approach. United States: N. p., 2012. Web. doi:10.1063/1.4767238.
Vos, Wiebe M. de, School of Physics, University of Bristol, Tyndall Avenue, BS8 1TL Bristol, Mears, Laura L. E., Richardson, Robert M., Cosgrove, Terence, Prescott, Stuart W., & Dalgliesh, Robert M. Measuring the structure of thin soft matter films under confinement: A surface-force type apparatus for neutron reflection, based on a flexible membrane approach. United States. doi:10.1063/1.4767238.
Vos, Wiebe M. de, School of Physics, University of Bristol, Tyndall Avenue, BS8 1TL Bristol, Mears, Laura L. E., Richardson, Robert M., Cosgrove, Terence, Prescott, Stuart W., and Dalgliesh, Robert M. Thu . "Measuring the structure of thin soft matter films under confinement: A surface-force type apparatus for neutron reflection, based on a flexible membrane approach". United States. doi:10.1063/1.4767238.
@article{osti_22093989,
title = {Measuring the structure of thin soft matter films under confinement: A surface-force type apparatus for neutron reflection, based on a flexible membrane approach},
author = {Vos, Wiebe M. de and School of Physics, University of Bristol, Tyndall Avenue, BS8 1TL Bristol and Mears, Laura L. E. and Richardson, Robert M. and Cosgrove, Terence and Prescott, Stuart W. and Dalgliesh, Robert M.},
abstractNote = {A unique surface force type apparatus that allows the investigation of a confined thin film using neutron reflection is described. The central feature of the setup consists of a solid substrate (silicon) and a flexible polymer membrane (Melinex{sup Registered-Sign }). We show that inflation of the membrane against the solid surface provides close and even contact between the interfaces over a large surface area. Both heavy water and air can be completely squeezed out from between the flexible film and the solid substrate, leaving them in molecular contact. The strength of confinement is controlled by the pressure used to inflate the membrane. Dust provides a small problem for this approach as it can get trapped between membrane and substrate to prevent a small part of the membrane from making good contact with the substrate. This results in the measured neutron reflectivity containing a small component of an unwanted reflection, between 10% and 20% at low confining pressures (1 bar) and between 1% and 5% at high confining pressures (5 bar). However, we show that this extra signal does not prevent good and clear information on the structure of thin films being extracted from the neutron reflectivity. The effects of confinement are illustrated with data from a poly(vinyl pyrollidone) gel layer in water, a polyelectrolyte multilayer in water, and with data from a stack of supported lipid-bilayers swollen with D{sub 2}O vapor. The data demonstrates the potential of this apparatus to provide information on the structure of thin films under confinement for a known confining pressure.},
doi = {10.1063/1.4767238},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 83,
place = {United States},
year = {2012},
month = {11}
}