Polymer Monolayer Dynamics - Functional Materials and Biomaterials - page 59

Polymer Monolayer Dynamics

Alan R. Esker 2 · Chanjoong Kim 3 ·HyukYu 1 (

)
1 Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA
[e-mail]
2 Present address:
Department of Chemistry, Virginia Polytechnic Institute and State University,
Blacksburg, VA 24061, USA
3 Present address:
Department of Physics & Division of Engineering & Applied Sciences,
Harvard University, Cambridge, MA 02138, USA

1 Introduction: Brief History of Monolayers .................. 60

2 Static r erties f ly er layers ................... 61

3 a illary ave y a ics ........................... 65

4 Surface Light Scattering Method ........................ 75

5 Polymer Systems ................................ 80

5.1 Homopolymers ................................. 80

5.1.1 VinylPolymersandPolyethers......................... 80

5.1.2 BinaryMonolayer:SideChainLengthEffect ................. 88

5.1.3 TemperatureDependence............................ 91

5.2 Copolymers ................................... 92

5.2.1 AlternatingCopolymers............................. 92

5.2.2 BlockCopolymers................................ 98

6 Other Methods for Monolayer Dynamics ................... 104

7 cl si s ................................... 106

References ....................................... 107

Abstract This is to review viscoelastic properties of monomolecular layers of polymers
on the air/water interface, as probed principally by surface light scattering. The method
is a non-invasive one that makes use of spontaneous capillary waves, induced by dens-
ity fluctuations within liquids under thermal equilibrium. The capillary waves are also
called ripplons, and they propagate with temporal damping. The interface is determined
to be molecularly smooth but still dielectric permittivity difference between air and wa-
ter is large enough to give rise to strong light scattering. Thus, the scattering amounts to
a surface analog of Brillouin scattering in bulk liquid wherein spontaneously propagating
phonons interact with light. Thus, the power spectra of scattered light from the interface
provide the propagation rate and the damping coefficient. Analysis is based on the reso-
nant mode-coupling of lateral and transverse waves that are recast into the lateral storage
modulus and the corresponding loss modulus. By virtue of the two-dimensional char-
acter of the monolayers, many intriguing observations have been made with respect to