(514f) Self-Assembly of Super-Stiff Adhesive Gels From Common Polyelectrolytes

Ionic crosslinking of polyelectrolytes with multivalent counterions can yield a wide array of self-assembled complexes. These complexes range from liquid coacervates to solid gels and attract widespread interest in fields such as controlled release, antibacterial coatings and water treatment. Here, we will show that certain mixtures of commonly-used polyelectrolytes and multivalent counterions can self-assemble into extremely stiff hydrogels (G’ ~ 10⁶ Pa). Such stiff gels, to our knowledge, have hitherto only been prepared through dense covalent crosslinking or via saloplastic processing of polyelectrolyte complexes, but never through spontaneous polymeric self-assembly. In addition to their high moduli, these gels are very adhesive and stick to a wide variety of substrates (including Teflon^®, skin and glass). The analysis of their formation via isothermal titration calorimetry (ITC), phase studies and rheology revealed that they typically form when the polymers and multivalent counterions are mixed at near-stoichiometric charge ratios and that their formation and dissolution can be triggered by changes in pH and ionic strength. The effects of polymer structure and polyelectrolyte/counterion affinity on the gel properties have also been examined and will be discussed in this talk.