1 Polymer Surfaces Group Laboratory for Surface Science and Technology Department of Materials ETH Zürich, Zürich, Switzerland. edmondo.benetti@mat.ethz.ch.
2 Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland. marcus.textor@mat.ethz.ch.
3 School of Chemical and Biomedical Engineering, College of Engineering, Nanyang Technological University, Singapore. hduan@ntu.edu.sg.