The self-assembly of (cyclic peptide)-polymer conjugates provide a versatile and functional platform for the precise design of polymeric supramolecular nanotubes. Moving the platform into aqueous media has been a recent accomplishment that has unlocked many exciting applications; but to complement these advances, we require better control over the structure (in particular, the length) of the nanotube. Here we propose to employ the use of electrostatic interactions to control the thermodynamic product, providing precise control over nanotube lengths and access to more complex nanostructures, such as barcoded and end-functionalised nanotubes.