The use of specular neutron reflection to study a wide variety of problems in surface and interfacial chemistry is introduced and discussed. Recent developments in neutron reflectometry instrumentation, and their implementation in the design of the SURF reflectometer at the ISIS pulsed neutron source, are described. The design of the SURF reflectometer has been optimised for the surface chemistry of soft matter and new experimental results that exploit the novel features of this second generation neutron reflectometer are presented and discussed in the context of the opportunities for future studies that the technique and the new instrumentation presents. The examples from the broad programme in surface chemistry include surfactant and polymer adsorption at the air/liquid and liquid/solid interfaces, adsorption at the liquid/liquid interface; Langmuir–Blodgett films and liquid crystalline alignment layers, thin solid polymer films and interfaces; liquid mixtures and in situ electrochemistry.

Plastics have transformed our modern world. With a range of outstanding properties, they are used in an ever-widening range of applications. However, the linear economy of their use means that a large volume of plastics is discarded after use. It is believed that approximately 80% of the estimated total 6.3 Bt of plastics ever produced have been discarded, representing not only a huge loss of valuable resources, but mismanaged waste is also the origin of an ever-increasing environmental disaster. Strategies to prevent loss of materials resources and damage to the environment are elements of a circular plastics economy that aims to maintain plastics at their highest value for the longest time possible and at the same time improve the economy and prevent detrimental environmental impact. The latter in particular is driving recent changes in policies and legislation across the world that are rapidly being introduced in order to solve these environmental issues. The achievement of a circular economy will require not only innovative technical developments, but also major economic investment and changes to business practice coupled with significant changes in social behaviour. This paper summarizes the complex and highly interrelated technical issues and provides an overview of the major challenges, potential solutions and opportunities required to achieve and operate a circular plastics economy. This article is part of a discussion meeting issue ‘Science to enable the circular economy’.

The width of the interface between two immiscible polymers, deuterated polystyrene and poly(methyl methacrylate), has been measured using neutron reflectivity as a function of the thickness of the deuterated polystyrene layer. A logarithmic dependence of interface width on film thickness is observed, characteristic of an interface broadened by thermal induced capillary waves, whose spectrum is cut off by dispersive interactions across the polymer layer. Reasonable agreement is obtained with the results of self-consistent field theory when suitably modified to account for capillary waves, resolving a long-standing discrepancy between theory and experiment.