Synthesis of polyelectrolyte nanocapsules (NCs) by interfacial crosslinking of surfactant monolayers adsorbed on crystallized miniemulsion nanodroplets is systematically studied by using surfactants with varied lengths of hydrophobic n-a lkyl tails. The results indicate that the n-a lkyl tails of surfactants need to possess at least sixteen carbon atoms, in order to obtain stable surfactant monolayers for achieving well-defined NCs. The structural control of NCs via crystallized miniemulsion systems is discussed.