Three-step decay of time correlations at polymer-solid interfaces

¹ Institute of Physics, Johannes-Gutenberg-University - 55099 Mainz, Germany, EU
² Institute of Physics, Martin-Luther-University - 06099 Halle, Germany, EU

^a wolfgang.paul@physik.uni-halle.de

Received: 10 February 2012
Accepted: 26 March 2012

Abstract

Two-step decay of relaxation functions, i.e., time scale separation between microscopic dynamics and structural relaxation, is the defining signature of the structural glass transition. We show that for glass-forming polymer melts at an attractive surface slow desorption kinetics introduces an additional time scale separation among the relaxational degrees of freedom leading to a three-step decay. The inherent length scale of this process is the radius of gyration in contrast to the segmental scale governing the glass transition. We show how the three-step decay can be observed in incoherent scattering experiments and discuss its relevance for the glass transition of confined polymers by analogy to surface critical phenomena.