Elastic Moduli of Thin Film Glasses

Surface wrinkling of thin glassy films is utilized to determine their elastic modulus. Similar to the glass transition temperature, the elastic modulus of polystyrene thin films decreases as the film thickness becomes comparable with the molecular dimensions. In order to better understand this phenomenon, the moduli of a series of small molecule organic glasses with well defined absorption spectra are determined as a function of film thickness. As the absorption spectra is related to the molecular packing, the relationship between the molecular density in thin films and their mechanical properties can be explored.