High Frequency Acoustics in Colloid Based Meso and Nanostructures by Spontaneous Brillouin Light Scattering This book deals with the exploration of phononic properties ofmeso and nanostructured colloid based composite materials at hypersonic (GHz) frequencies. It contains new research results in the emerging field of phononics. The present thesis deals with the exploration of phononic properties ofmeso and nanostructured colloid based composite materials at hypersonic(GHz) frequencies. The emerging field of phononics the mechanical analogue of photonics treats the propagation and manipulation of acoustic waves in structured materials. Due to their widely tunable properties (size density etc.) and their ability to self assembly polymer colloids are ideal systems to realize hypersonic phononics which are investigated by Brillouin light scattering herein. Therefore both the mechanical and physical properties of the individual colloidal particles which manifest in their resonance vibrations (eigenmodes) as well as the acoustic propagation in colloidal structures have been investigated.This thesis already lead to several journal publications and seven presentations at international conferences and was honored summa cum laude.