Laser Doppler Electrophoresis applied to colloids and surfaces

The colloidal state is often taken for granted and yet it surrounds us in both home and in the workplace. Coating technologies, drug delivery systems, cleaning and personal care formulations all rely on discrete well controlled physical properties at several distance scales in order to derive the desired product performance, and are reliant on an in-depth knowledge of the surface of interest. Techniques such as dynamic light scattering and Laser Doppler Electrophoresis are readily available to the experimenter who can perform a measurement without the need for in-depth knowledge of the technique and is finding ever-increasing applications. Although the actual means of determining mobility using LDE has not changed much, these are exciting times in that good instrumentation and sample environment, together with high quality method development all combine in a robust platform enabling new science and stronger engagement with industry. In this review, we report on the current state of the application of LDE, both in standard and advanced formats. There is the alliance of LDE and neutron scattering to study polymer surfactant interactions, advances in the measurement of protein electrokinetics, novel approaches to the study of surface zeta potential, and progress towards measurements in high concentration dispersions are all reported and discussed. We also report on recent advances where industrial applications in-line have resulted in cost savings and reduced environmental impact. It is our observation that industrial and academic users are asking questions which require the fundamentals of the instrumentation and its capabilities and limits to be better communicated and understood, and this has resulted in a doubling of the number of publications featuring LDE to similar to 1300 over the last several years. Particular areas of growth are biomedical, drug delivery, fast moving consumer goods, engineered nanoparticles, toners and printing technology. (C) 2015 Published by Elsevier Ltd.