Brillouin Scattering Studies of Polymeric Nanostructures

For a range of applications, polymers are now being patterned into nanometer-sized features. In these applications, the robust mechanical properties of the nanostructures are critical for performance and stability. Brillouin light scattering is presented as a nondestructive, noncontact tool used to quantify the elastic constants in such nanostructures. We demonstrate this through a series of thin films and parallel ridges and spacings (gratings) with ridge widths ranging from 180 to 80 nm. For the set of films and structures presented here, the room-temperature elastic moduli did not change with decreasing film thickness or grating ridge width, and this implied that one-dimensional and two-dimensional confinement-induced changes of the mechanical properties were not significant down to feature sizes of 80 nm. Additionally, Brillouin spectra of submicrometer gratings revealed new modes not present in the spectra of thin films. The origin of these new modes remains unclear.