聚丙烯酰胺

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聚丙烯酰胺The behavior of polymers at interfaces is a subject of
fundamental importance for a wide range of research
areas and applications. These include， for instance，
adhesion， lubrication， flocculation， and colloidal stabi-
lization. In addition， biological macromolecules play a
significant role at natural and artificial interfaces， such
as cell membranes and implants， respectively. Since
they are water-soluble and inexpensive， polyacrylamide
polymers have received the attention of many indus-
tries. In addition， polyacrylamide can be easily modified
and， therefore， covers a wide range of properties. Some
applications in industry can be found in oil recovery， in
paper fabrics， and in water purification. In many of
them， polyacrylamide adsorbs to surfaces and modifies
them accordingly.
The lack of experimental techniques capable of verify-
ing theoretical concepts on polymer conformations at
interfaces has led to a limited level of understanding
in that field. Neutron scattering and reflectivity， surface
forces apparatus (SFA)，
1，2
ellipsometry， and X-ray pho-
toelectron spectrometry have provided some insights
into the subject. However， several shortcomings， such
as the need of a vacuum for some techniques or limited
lateral resolution， leave many questions unanswered.
With the development of scanning probe microscopy
(SPM) techniques by Binnig et al.， in particular， the
atomic force microscope (AFM)
3
the technique used in
this work， polymer molecule interactions and conforma-
tions of single polymer chains can be studied directly
on the nanometer scale.
In polymer science the AFM was first used to image
polymer crystals with contact mode atomic force mi-
croscopy
4
followed by the imaging of single polymer
molecules with contact mode5，6
and intermittent contact
mode AFM.7-9
One of the main advantages of using the
AFM for the investigation of polymers at interfaces is