Closed-looped micelles in surfactant tetramer solutions

Formation of a dominant population of closed loops in wormlike micellar sys tems, theoretically predicted but never reported so far, is achieved with a new cationic surfactant tetramer, The contour length distribution N(L) of the closed-looped micelles is determined by transmission electron microscop y at cryogenic temperature. At large contour lengths, the distribution obse rved scales as N(L) proportional to L-5/2, as expected from ring-chain equi librium polymerization theory. At small contour lengths, the rigidity-depen dent ring closure probability provides a direct estimate of the persistence length. These results re-emphasize the new possibilities offered by surfac tant dimers (gemini) and oligomers in obtaining new morphologies in self-as semblies.