Abstract
Roughness and wetness can disrupt interfacial bonding and reduce adhesion, and this phenomenon is of relevance for many biological and engineering applications. I will discuss how roughness affects both dry and wet adhesion as well as provide an overview of our current theoretical understanding in this area. My specific interest is in underwater adhesion, focusing on overcoming the challenges for achieving adhesion in confined water, which reduces molecular contact (particularly when in contact with rough surfaces). The trapping of confined water is a function of roughness, surface chemistry, and kinetics, making this a difficult problem to explain using theoretical models. Interestingly, nature has developed a wide range of strategies that enable organisms to stick to rough and wet surfaces. For example, geckos and insects use fibrillar structures to create molecular contact and to improve water drainage, spiders use hygroscopic salts to reduce interfacial water next to hydrophilic surfaces, and mussels use specific chemical groups (catechol) to bind to polar surfaces. I will share new strategies inspired by these natural systems for improving adhesion and discuss how they are applied to biomedical and engineering applications that require adhesion to wet and rough surfaces.