10. Self-assembling Hydrogels from pH-Responsive Ionic Block Copolymers

Hydrogels are three-dimensional (3D) soft materials that consist of a solid matrix (usually a three-dimensional network) entrapping high content of water (more than 90 wt%). This remarkable feature makes them suitable for many applications especially in medicine as drug carriers and tissue engineering scaffolds. As far as polymeric matrices are concerned, two main strategies for achieving 3D network structures can be distinguished. The first one relies on the covalent bonding of hydrophilic polymer chains, leading to hydrogels referred as chemical networks. The second approach deals with the self-assembly of tailor-made segmented macromolecules via reversible weak interactions, namely hydrophobic, ionic, π–π staking, and so on, that leads to the so-called self-assembling hydrogels. The use of reversible (physical) cross-links allows the design of “smart” soft materials that can response to their environment (e.g., pH, ionic strength, temperature, shear). This chapter is devoted to the self-assembling hydrogels arising from associative block copolymers bearing ionic or ionogenic blocks, namely polyelectrolytes or polyampholytes. This specific feature endows the hydrogels with responsiveness to pH and ionic strength which make them attractive soft materials for potential biomedical applications.