2019 Impact factor 1.812
Soft Matter and Biological Physics


Eur. Phys. J. E 8, 129-136 (2002)
DOI: 10.1140/epje/i2000-10102-5

Using adhesion to probe viscoelasticity of polymer film surfaces: A quartz crystal microbalance study

J.A. Forrest1, J. Mattsson2 and L. Börjesson2

1  Department of Physics and Guelph-Waterloo Physics Institute, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1
2  Department of Experimental Physics, Chalmers University of Technology, SE-412 96, Göteborg, Sweden

jforrest@uwaterloo.ca

(Received 28 August 2000 and Received in final form 17 September 2001)

Abstract
We have used a quartz crystal microbalance to monitor the adhesion of small particles to the surface of polystyrene films. This technique is shown to provide a signature of viscoelastic relaxation processes at the polymer surface. For $M_{\rm n}$ values less than 104 and greater than 105, this signature occurs at a temperature $\sim 12.5$ K above the measured bulk glass transition temperature, $T_{\rm g}$. For intermediate values of $M_{\rm n}$ however, the relaxation signature occurs at temperatures as low as 7 K above the bulk $T_{\rm g}$. This observation suggests a slight decrease in the $T_{\rm g}$ value near the polymer surface. A model incorporating the effects of enrichment of polymer chain ends at the free surface was considered and found to provide a quantitative description of the data.

PACS
64.70.Pf - Glass transitions.
68.35.Np - Adhesion.
68.35.Gy - Mechanical properties; surface strains.
82.35.Lr - Physical properties of polymers.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002