L-Phenylalanine-N-carboxyanhydride (L-Phe-NCA) was synthesized from bis(trichloromethyl)-carbonate and L-phenylalanine. Octadecyl-L-phenylalanine oligomer was obtained by the ring-opening reaction of L-Phe-NCA using octadecylamine as initiator. The average polymerization degree of the oligomer is 5 determined by ¹H NMR. The oligomer can aggregate and self-assemble to form thermal reversible physical gels in some organic solvents. It can form transparent gels in chlorobenzene, toluene and diphenyl ether and but non-transparent gels in the solvents such as benzene, nitrobenzene and butyl acrylate. The minimum gelation concentration of the oligomer in these organic solvents is in the range of w＝0.3%～1%. The morphology and structures of oligomer aggregated in the media were characterized by XRD, FE-SEM and molecular simulation. The results indicated that hydrogen bonding and π-π stack were main driving forces for the self-assembly of oligomer. The aggregates of oligomer were tape-like with thickness of approximate 20 nm. The solvent molecules were immobilized by capillary force in the entangling network.

Key words: L-phenylalanine, oligomer, gelator, self-assembly