Experimental evidence for interplay of dynamic heterogeneity and finite-size effect in glassy polymers
Department of Physics, Indian Institute of Science, 560012, Bangalore, India
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Accepted: 8 July 2011
Published online: 23 September 2011
Despite two decades of extensive research, direct experimental evidence of a dynamical length scale determining the glass transition of confined polymers has yet to emerge. Using a recently established experimental technique of interface micro-rheology we provide evidence of finite-size effect truncating the growth of a quantity proportional to a dynamical length scale in confined glassy polymers, on cooling towards the glass transition temperature. We show how the interplay of variation of polymer film thickness and this temperature-dependent growing dynamical length scale determines the glass transition temperature, which in our case of 2–3 nm thick films, is reduced significantly as compared to their bulk values.
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2011