Titre de la dissertation: « Characterization of the mechanical and viscoelastic properties of soft materials for bio-inspired applications ».

 Promoteur de thèse: Monsieur Philippe Leclère

Résumé de la dissertation: Mother Nature has bestowed upon us a wonderful gift – an advanced brain capable of observation, reasoning, and creativity. As humanity turned its gaze towards the natural world, it discovered a wealth of inspiration, from the orderly hexagonal structure of honeycombs to the intricate beauty of snowflakes. Each of these natural structures hides the biophysical explanations, such as the hexagonal honeycomb’s efficiency in honey storage, minimizing beeswax usage and energy expenditure. In contrast, the diverse crystalline patterns of snowflakes are dictated by temperature and atmospheric moisture levels, with the hexagonal plate being the most common shape at sub-freezing temperatures.

However, our curiosity with nature goes beyond what the human eye can see and into the realm of tiny, microscopic structures. Due to this, the microscope was created, enabling us to study the world of nanoscale organisms, bacteria, DNA, proteins, and ribosomes. Atomic force microscopy (AFM) has been used to examine the nanoscale material shape and other material properties like mechanical, electrical, magnetic and spectroscopic properties, offering deeper insights into this microscopic domain.

In this thesis, we explore the nanoscale structure, mechanical and viscoelastic characteristics of polymers throughout a wide range of materials, from natural to synthesized. We initiate our inquiry by examining the formation of natural polymers derived from barnacle cement proteins under varying conditions, including different times and pH levels. This research could illuminate the adhesive capabilities of these natural polymers in underwater settings, with potential applications in marine engineering, biofouling prevention, and biomedicine. Continuing our investigation, we pivot towards understanding the conformation and mechanical properties of synthetic polyacrylamide (PAA) hydrogels. This exploration seeks to broaden our knowledge of tissue engineering and cell mechanics, potentially leading to the development of superior scaffolds and biomaterials for tissue regeneration and repair. Finally, our focus turns to acrylate copolymers, delving deeper into their nanostructure and viscoelastic properties. This inquiry aims to evaluate their suitability as sustainable sources for next-generation cosmetic materials. By comprehending the nano-level interactions and viscoelastic properties of these copolymers, we can create environmentally friendly cosmetic materials with enhanced performance.

Through our comprehensive examination of natural polymers, synthetic hydrogels, and acrylate copolymers, this research contributes significantly to the field of polymer science. By uncovering the mechanisms behind nanostructure formation and exploring the viscoelastic properties of these polymers, we unlock new avenues for advancements in diverse fields, from tissue engineering and marine engineering to sustainable cosmetics.