The glass transition in thin polymer films

In this article, we present a detailed account of important recent developments in the rapidly evolving area of glass transitions in thin polymer films. We review the case of polymer films supported by substrates, and show that a definite experimental consensus exists. We consider recent results from experimental studies of free-standing films of polystyrene. These studies have provided a thorough quantification of the behavior of glass transition anomalies in free-standing polymer films, and have served to motivate recent attempts at theoretical descriptions. We introduce and examine models, which have been proposed to explain the experimental observations and discuss the significance of these models.