Communication: Evidence of dynamic heterogeneity in glassy polymer monolayers from interface microrheology measurements

Increased humidity can soften glassy Langmuir polymer films by two mechanisms: plasticization of the polymer material, and suppression of the evaporation cooling effect

Increasing the relative humidity decreases the surface pressure of a glassy Langmuir polymer film.

Experimental evidence for interplay of dynamic heterogeneity and finite-size effect in glassy polymers

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.