1. Laboratory of Polymer Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
2. Sasol Technology, R&D, 1Klasie Havenga Street, Sasolburg, 1947, South Africa
3. Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X 1, Matieland, 7602, South Africa