Solid-like dynamics in ultrathin films of polymeric liquids

In this letter, we demonstrate that, at mesoscales, nonferroelectric liquid films of poly(dimethyl siloxane) exhibit significant electrostriction not present in the corresponding bulk state. Remarkably, the observed electrostrictive effect has a response time <20 mus in contrast to >5 ms recorded in conventional bulk (ferroelectric) polymers. The emergence of this fast electrostrictive strain in thin films is explained in terms of the amalgamation of two contrasting dynamic features-the influence of a highly mobile, viscous layer (at the air/film interface) on the less-mobile, but fast responding, solid-like layer at the film/substrate interface. The effect is observed for thickness below 200 nm. (C) 2003 American Institute of Physics.