From Surfactants to 3D Printing: How Ion-Chelator Pair Interactions Affect the Mechanical Properties of Bioinspired Materials

The remarkable adaptability observed in marine ecosystems has often inspired researchers when developing new soft materials. The research undertaken in this thesis explores how ion chelator pair interactions influence the mechanical properties of bioinspired materials across various length scales, encompassing nanometer-sized membranes to centimetre-sized 3D printed structures. The research starts by addressing the crucial role of surfactants in stabilising emulsions for various applications, such as in food and cosmetics. A cost-effective synthesis for diblock perfluorinated copolymer surfactants is introduced to identify the optimum ratio of the hydrophilic to the hydrophobic block sizes for the stability of water-in-perfluorinated oil emulsions. Building upon this knowledge, the synthesised surfactants are functionalised with catechols, inspired by the mussel byssus, to produce capsules with thin, viscoelastic membranes through ionic crosslinking. These membranes, formed at the liquid-liquid interface, exhibit self-healing properties and impermeability to small molecules, holding potential for biomedical applications such as in vitro cell studies. Extensive studies on the influence of different catechol derivatives and cross-linking ions on the rheological properties of these membranes provide insights into their stability and mechanical behaviour. The understanding gained from membrane studies is further extended to ionically crosslinked bulk hydrogels, indicating the transferability of knowledge from bulk hydrogels to the design of adhesive and self-healing capsules with tunable mechanical properties. Finally, the research applies the understanding of ionic crosslinking to enable the 3D printing of granular inks in aqueous environments. By leveraging electrostatic interactions, single-network granular hydrogels are successfully printed in water, showcasing rheological properties and stability that are similar to their counterparts printed in air. These granular hydrogels are recyclable due to the reversible electrostatic interactions between adjacent microparticles. This approach is promising for sustainable soft material fabrication, particularly in underwater applications, thereby expanding the horizons of 3D printing possibilities.Overall, this thesis contributes insights into the synthesis, properties, and applications of soft materials, laying a foundation for advancements in diverse fields and addressing the pressing need for sustainable material solutions.