title: Materials science. Polymers go with the flow.
abstract: The flow of polymer melts and solutions differs substantially from that of other liquids, because the long polymer chains can become entangled and cannot cross each other freely in their motion. In his Perspective, Marrucci provides an overview of theoretical attempts to explain polymer flow. He highlights the report by Bent et al., who have performed sophisticated experiments on linear polymers that prove key elements of the latest theory. Furthermore, the approach used by the authors will become an important experimental tool for investigating more complex polymer systems.