The use of polymers as barrier materials is one of their widest and most important fields of application (e.g., fuel tanks and hoses, water circuits, food packaging, raincoats and umbrellas, electrical insulation, drug delivery), and their performance also has environmental implications. In consequence, the problems of sorption and diffusion in polymers are important and ubiquitous in everyday life as well as in a number of high-tech applications. This book covers the science involved in these topics, which are often studied only from an engineering point of view. “Sorption and Diffusion in Polymers” presents the different models generally used to describe sorption and/or transport properties and also a new physical model for them. It provides an overview of relevant applications, related polymer families, and the strategies used to control or reduce sorption and diffusion in polymer materials. This edited work details the latest research on the topic, with chapters written by experts in the field.