Freezing Of Nano-Scaled Fractal Molecules: Dendrimers

Within this paper we present mono-disperse dendrimers as a new class of ideal canonical glass formers where the frustration mechanism originates from the self similar intramolecular order. Because of their fractal intramolecular structure these dendrimers are hardly able to build up a three dimensional translation symmetry necessary to form the crystalline state. Instead they show an unconventional dynamic and static freezing behavior at rather low temperatures. Based on temperature modulated differential scanning calorimetry (TMDSC) and Brillouin spectroscopy (BS) we give further evidences for the existence of an ideal primary glass transition with a thermal glass transition temperature which increases with the generation index of the fractal molecule. However, the primary glass transitions of higher generations do not completely erase the memory of the fractal intramolecular mobility but allow the survival of dynamic processes significant for the freezing of the constituting molecular unit.