ABSTRACT
For over two decades, numerous studies have reported large shifts in the glass transition temperature Tg with confinement of the system to nanoscale dimensions [1-13]. These shifts in Tg can be several tens of kelvin in size and occur in either direction (up or down relative to bulk Tg) leading to enhanced or suppressed dynamics depending on the system. Although most heavily studied in polymers, similar phenomena are observed in small-molecule glass formers [1,8,14,15] and colloidal systems [16-21], indicating some universality to these effects. Other material properties related to Tg such as physical aging [22-29] and modulus [30-40] also tend to show changes with confinement at the nanoscale. Knowledge of these effects is important to our fundamental understanding of the glass transition, the development of technological applications such as microelectronic circuits [41-44] and gas separation membranes [29,45], and water dynamics in biological processes [46,47].
