A team of scientists from Twente was able to solve a hundred-year-old riddle concerning the formation of polyelectrolyte complexes (PECs) with NMR and are now able to measure and even predict what a PEC looks like on a molecular level.

You may not have heard of polyelectrolytes, but their complexes (PECs) play important roles in biological processes and can serve as a basis for new materials. ‘Polyelectrolyte complexes form when you mix two solutions of oppositely charged polymers together’, explains Giulia Allegri, PhD student in the group of Associate Professor Saskia Lindhoud at the University of Twente. ‘A PEC system consists of two phases, a solid polymer-rich phase and a supernatant phase with a lower concentration of ions and polyelectrolytes. When the polyelectrolytes mix and form a PEC, they release their counterions.’ But the exact distribution of all the different components and how they interact has been a mystery since PECs appeared on the scene a century ago. Allegri, Lindhoud, and their colleagues Jurriaan Huskens and Ricardo Martinho pose a solution to this riddle in a recent article in the Journal of Colloid and Interface Science.