Dewetting of Thin Organic Glass films below Tg

highlight_2.14_seed7Rob Riggleman and Zahra Fakhraai (Seed)

A 5nm layer of an organic glass (Tg= 28K) was produced by physical vapor deposition. The film’s morphology evolves with time at the isothermal annealing temperature of  T=293K=Tg-35K. The dewetting process resembles spinodal dewetting and the evolution of the structure can be used to evaluate the viscosity of the film.

At Tg-35K, the relaxation time of the bulk glass is longer than 104 S, while the estimated relaxation time of the 5nm film is less than 1S. The enhanced mobility, as measured by lower viscosity in these thin films is unprecedented and can explain why the process of physical vapor deposition can produce exceptionally stable glasses.