Quantitative Nanorheometry of Ultrathin Polymer Films

Direct mechanical property measurement of ultrathin polymer films is relevant for applications in lithography, micro-fluidic devices, and organic electronics. Traditional mechanical tests are generally unable to provide quantitative information at these length scales. While there has been extensive work measuring the Tg of these thin films using ellipsometry and other methods, there has been less work directly measuring other mechanical properties. In this work, the quartz crystal microbalance as a high frequency rheometer to measure the mechanical response of an ultrathin polymer film confined between a gold surface and a ridged over-layer. In this way, the shear compliance values of ultrathin films with thickness as low as 10 nm were measured directly.