2011, pp 1385-1408



There is a pervading presence of adhesive joints in nature. Adhesive secretions are used by organisms for attachment, construction, obstruction, defense, and predation. Most natural materials are hybrid materials combining organic and inorganic building blocks. Bioadhesives are able to build durable interfaces between hard and soft materials, often of disparate scales, and exhibit a certain number of characteristics that make them differ greatly from synthetic adhesives. The title of this chapter (Bioadhesives) includes a broad variety of different concepts: natural adhesives, biological adhesives, biocompatible adhesives, and biomimetic and bioinspired adhesives. The term natural adhesive describes substances that are formulated from partially or totally bio-based raw materials, which are employed as adhesives in man-made technology, but are not substances used by biological systems as glues. The term biological adhesive refers specifically to adhesive secretions of natural organisms in marine and other wet environments, or those produced on land. A different concept refers to what is named as biocompatible adhesive, including any natural or synthetic adhesive that interfaces with living tissues and biological fluids, and is suitable for short-/long-term biomedical applications. Specific mechanisms of adhesion found in nature are discussed – interlocking, suction, friction, dry and wet adhesion, gluing – to get inspiration for the development of new synthetic adhesives. Biomimetic adhesives are synthetic adhesives design to closely mimic the molecular structure and mechanisms of adhesion found in nature. Bioinspired adhesives are synthetic adhesives whose design is inspired in biological concepts, mechanisms, functions, and design features. Also the promising technology of self-healing polymers is reviewed, as an effective method for controlling crack propagation and debonding.