INTRODUCTION
The importance of tribology, the science of friction, wear, and lubrication, can hardly be overstated. It plays a crucial role in almost all human activities and natural phenomena. For example, the interaction between rubber and road surfaces is critical for safe walking and driving. Too little friction in these scenarios can lead to catastrophic events, such as car accidents or slips and falls. In fact, slips, trips, and falls are a leading cause of both non-fatal and fatal occupational accidents, resulting in significant work absences and indirect economic losses. Beyond this, in mineral mining, a staggering 40% of consumed energy is attributed to friction alone. The economic implications of friction and adhesion are immense, with the global lubricant market valued at nearly $20 billion annually.
Understanding and controlling friction and adhesion has been a subject of interest for centuries, spanning multiple scientific disciplines. This complex field requires knowledge of intermolecular interactions, mechanics, and rheology, necessitating contributions from physics, chemistry, and engineering. The study of these phenomena encompasses a broad range of length scales, from sub-nanometer to macroscopic, making it a particularly challenging and fascinating area of research. Over time, the study of friction and adhesion has evolved from empirical observations to sophisticated multiscale modeling and advanced experimental techniques. At present, these phenomena are recognized as critical in fields ranging from nanotechnology to geophysics.
Recent advancements in research are bridging the gap between fundamental understanding and practical applications, addressing challenges in energy efficiency, materials science, and biotechnology. By improving our understanding of these phenomena, we can develop more efficient motors, enhance safety in various industries, and reduce energy consumption across multiple sectors. As we continue to explore and unravel the complexities of friction and adhesion, it is crucial to stimulate broader community engagement and bring new ideas to the field. By combining insights from various disciplines and leveraging both experimental and theoretical approaches, we can work toward innovative solutions that address the challenges posed by friction and adhesion in our modern world. This special collection is both timely and important as it showcases cutting-edge research that bridges the gap between fundamental understanding and practical applications, addressing challenges in energy efficiency, materials science, and biotechnology.
SUMMARY OF AREAS COVERED
This special collection spans a wide range of topics within friction and adhesion research.
Novel materials and coatings
Several articles explore innovative materials and coatings for controlling friction and adhesion. The fabrication of liquid-like polydimethylsiloxane coatings for ice adhesion resistance offers promising solutions for cold climate applications.1 Another study investigates gradient-stiffness hydrogel layers, revealing how fewer polymer chains can paradoxically lead to higher adhesion through network stretching.2
Biological and bio-inspired systems
This collection delves into biological adhesion mechanisms, with a fascinating study on the particle binding capacity of snail saliva.3 This research not only enhances our understanding of biological adhesives but also paves the way for bio-inspired adhesive solutions.
Tribology at different scales
From nanoscale to macroscale, this collection covers various aspects of tribology. Molecular simulations of sliding on SDS surfactant films provide insights into nanoscale lubrication,4 while studies on ice breakloose friction5 and sliding friction on ice6 address macroscale phenomena crucial for winter sports and transportation.
Fluid–solid interactions
Several papers investigate the complex interactions between fluids and solids in adhesion and friction contexts. The effect of fluid viscoelasticity, shear stress, and interface tension on lift forces in lubricated contacts is explored,7 as well as the fascinating phenomenon of out-of-contact peeling caused by elastohydrodynamic deformation during viscous adhesion.8
Advanced manufacturing and surface engineering
This collection includes cutting-edge research on manufacturing techniques for creating surfaces with specific friction and adhesion properties. A notable example is the experimental and simulation study of laser–electrochemical hybrid manufacturing of micro-/nano-symbiotic superamphiphobic surfaces.9
Theoretical advancements
CONCLUSIONS
This special collection represents a significant step forward in our understanding of friction and adhesion phenomena. By bringing together diverse perspectives and methodologies, from molecular simulations to experimental studies, it offers a comprehensive view of the current state of the field. We hope that this collection will not only serve as a valuable resource for researchers but also inspire new directions in friction and adhesion research, ultimately leading to innovative solutions for real-world challenges.
ACKNOWLEDGMENTS
We extend our sincere gratitude to all the authors who contributed their outstanding research to this special collection. We also thank the editorial team of the Journal of Chemical Physics for their support and guidance throughout the process. Special thanks go to the reviewers whose insightful comments helped shape and refine the manuscripts.
