Institut Charles Sadron Event

The aim of this CIFRE PhD work in collaboration with URGO is to develop a sprayable biomaterial based on hydrogel foams. The core theme of this PhD is built on understanding the link between the physical chemistry (formulation of the continuous phase, foam stability) and physics (structure and mechanical properties) of hydrogel foams both in the liquid and solid state. We first investigate the foaming of highly viscous polymer solutions showing that foaming through a porous medium is able to generate foams of high gas fraction and small bubble size as required for this project. We then investigate conventional methods for alginate gelation (relying on the use of an inactive form of the cross-linker protected by a carrier until acidification of the medium), demonstrating the influence of the release process of the cross-linker on the mechanical properties of the resulting hydrogel. We show for the first time the competition between the acidifying agent and the alginate in binding with the cross-linker and therefore provide a basis for the efficient design of alginate hydrogels. We also introduce a novel gas-initiated gelation route which consists in a one-step process using CO2 for simultaneous foaming and gelation. After demonstrating that this method is unsuitable for the development of the desired material, we establish a base for the development of a stable gelled alginate foam with controlled morphology whose optimisation will be pursued by URGO for the purpose of the final application.