"This project is intended to lead to the identification, design and development of a novel, economically viable pre-industrial process, to make the world's toughest synthetic fibres. Our new concept to obtain fibers with unconventional toughness is indeed very simple and robust: the introduction in high-strength fibers of a smart frictional element, in the form of a large slip loop in a slider, that in its simplest configuration is a knot. A preliminary proof of concept implementation has already been performed, realizing the highest toughness value for a fiber to date, using commercial Zylon® and reaching 1400 J/g, surpassing for the first time 1000 J/g. This knot-based manufacturing strategy is already a milestone of the ERC Starting Grant ""Bio-inspired Hierarchical Super Nanomaterials"" (BIHSNAM), and it has proven to be an extremely simple yet efficient way for the production of ultra-tough materials. Instead of pursuing the synthesis of new materials, we fully exploit the potential of already existing ones, with an evident improvement in the potential quality of current industrial production, exploiting a relatively uncomplicated and economical, and therefore industrially attractive method. The aim of KNOTOUGH is therefore to optimize (identifying the proper slider element, e.g. knot topology, for maximizing toughness), consolidate and develop this manufacturing procedure, taking it to a pre-commercial stage, with potential applications in all those industrial manufacturing sectors where energy absorption is important (e.g., sporting goods, automotive, aerospace, protective devices)."