(122a) Ultra-Stable Structured Polymeric Glasses

The density and stability of a glass are strongly correlated with the principal viewpoint being that low-density glasses are unstable.  Upon heating, the structure of a low-density glass can abruptly collapse into a more dense state.  This collapse can be dramatic, e.g., resulting in glasses with negative thermal expansion coefficients upon heating within a certain temperature interval.  The distinctive advantage of low-density glasses in technologies, i.e., weight reduction, is obviated by their structural instability. A fundamental challenge is thus the development of strategies to manipulate – then arrest – the structure of low-density glasses to improve their stability.  Here we demonstrate that Matrix Assisted Pulsed Laser Evaporation (MAPLE) can be used to fabricate polymer glasses with extraordinarily low densities and simultaneously exceptional thermal and kinetic stability.  In addition, these glasses have significantly enhanced glass transition temperatures.  This unique (and unprecedented) combination of properties is a result of the glass morphology, i.e., the glasses are nano-structured.  The unique set of properties of MAPLE-deposited glasses may make them attractive in technologies where weight and stability are central design issues.