Self-assembly of flat nanodiscs in salt-free catanionic surfactant solutions

Discs of finite size are a very rare form of stable surfactant self-assembl y. It is shown that mixing of two oppositely charged single-chain surfactan ts can produce rigid nanodiscs as well as swollen lamellar liquid crystals with frozen bilayers. The crucial requirement for obtaining nanodisc self-a ssembly is the use of H+ and OH- as counterions. These counterions then for m water and lower the conductivity to 10 microsiemens per centimeter. In th e case of cationic component excess, a dilute solution of nanodiscs is in t hermodynamic equilibrium with a lamellar phase. The diameter of the cationi c nanodiscs is continuously adjustable from a few micrometers to 30 nanomet ers, with the positive charge Located mainly around the edges.