SANS will be used to determine the structure of nanotube dispersions formed by H-bond stacking of cyclopeptides coated with a sheath of stabilizing polymer. Cyclopeptide stacking favours infinitely long nanotubes, but their length and diameter are modulated by solvent interactions, by monomer type and degree of polymerization, and by temperature. By varying mixed solvent composition from trifluoroacetic acid, in which no self-assembly occurs, through to (deuterated) dimethylformamide and tetrahydrofuran, we will measure the size and core-shell nanostructure of these nanotubes, including solvent access to the internal cavity and the structure of and chain conformation the polymeric sheath. Structures in mixed systems and mixtures with specifically-designed capping agents will be investigated as a mechanism to control length and polydispersity of the nanotubes.