John Severn completed his Ph.D. at the University of Sussex and joined the group of Prof. R. van Santen at the Eindhoven University of Technology as a postdoc, working on the immobilization of alpha-olefin polymerization catalysts and the use of silsesquioxanes as homogeneous models. Then he joined the Dutch Polymer Institute working on the immobilization of single-site alpha-olefin polymerization catalyst, and with Avantium Technologies B.V. developing high throughput experimentation techniques for polyolefin catalysis. Since 2005 he has been a researcher at Borealis Polymer Oy, Finland. John Chadwick received his Ph.D. from the University of Bristol, after which he joined Shell Research in Amsterdam. Following the formation of Montell Polyolefins, he transferred from Shell to the Montell (now Basell) research center in Ferrara, Italy, with special responsibility for fundamental Ziegler-Natta catalyst R&D. In 2001, he joined the polymer chemistry group at the Eindhoven University of Technology as Programme Coordinator for research on polyolefin catalysis and catalyst immobilization.