Wetting‐Empowered Surface Functions for Engineering Applications

Abstract

One of the main characteristics of a surface is its ability to be wetted by a liquid. Surfaces can be explicitly designed for full or poor wetting by different liquid types or for the easy sliding or sticking of droplets. The design of functional surfaces crosses multiple length-scales and includes surface chemical functionalization, micro/nano-engineered surface structures, chemical/physical gradients, elasticity, etc. These design features form the basis for even more complex functionalities. Recent approaches have involved increasingly complex surface architectures and techniques such as controlling droplet shape/motion on slippery liquid-infused porous surfaces (SLIPS), and reducing lateral adhesion by employing the Leidenfrost phenomenon (article number 202001249). The importance of this research is underpinned by its role in resolving global challenges, such as environmental crises, sustainable energy, food and water production and consumption. Established in 2013, the Smart Materials and Surfaces Laboratory (SMSL) in Northumbria University has achieved considerable progresses in the areas of bio-inspired surface/interface science, smart materials, microdevices and systems, leading to a well-recognized profile in scientific significance and academic impact worldwide. The origin of this special issue is based on discussions among Prof. Butt, Prof. Xu, Dr. Li, and Dr. Smith, starting at the Droplets 2019 conference, which was co-organised by the SMSL. At last, we hope this collection of papers provides an interesting benchmark for wetting-empowered technological developments toward the discovery of frontier engineering applications. We appreciate the support from the whole editorial team of Advanced Materials Interfaces and the reviewers. We would like to gratefully acknowledge the contributions from all authors and their co-authors to this special issue, at this unprecedent time. Ben B. Xu is a Professor of Materials and Mechanics and Director of Research and Knowledge Exchange in the Department of Mechanical and Construction Engineering at Northumbria University, UK. Ben obtained his Ph.D. in Mechanical Engineering (2011) at Heriot-Watt University in Edinburgh, then moved to the University of Massachusetts, Amherst (US), to work (2011–2013) with Prof. Ryan C. Hayward as a postdoc. Since joining Northumbria in 2013, Ben has established a multidisciplinary research profile with diverse interests in responsive materials/surface, soft matter, materials chemistry, mechanics, energy materials and technology, and micro-engineering. Yifan Li was appointed as a Senior Lecturer in the Department of Mechanical and Construction Engineering at Northumbria University (UK) in 2014, having been a Research Fellow at the School of Engineering, University of Edinburgh (UK) where he also gained Ph.D. degree in 2008. He studied Engineering with a B.Eng. degree obtained from the School of Electronics and Electrical Engineering at Shanghai Jiao Tong University, Shanghai, China in 2003. Yifan's research interests are droplet microfluidics, microsystems, flexible electronics and transducers. Hans-Jürgen Butt is a director at the Max Planck Institute for Polymer Research (MPIP), Mainz, Germany. He studied physics in Hamburg and Göttingen. He defended his Ph.D. thesis in 1989 at the Max Planck Institute for Biophysics (MPIBP). After one-year postdoc experience at the University of California, he moved back to MPIBP and habilitated in 1995. In 1996, he became an associate professor at the Johannes Gutenberg-University in Mainz. In 2000, he became a full professor at the University of Siegen for Physical Chemistry. In 2002, he joined MPIP as a director working on soft matter interfaces.