Viscosity measurements were carried out using an Anton Paar Physica MCR101 rheometer. Measurements were performed using a 50 mm cone geometry (CP50) with gap distance between the geometry and the plate set to 0.101 mm and temperature set to 25 °C. All samples were poured onto the plate to minimise shearing that would be caused by pipetting the solutions. Fresh solution was used for all runs, unless otherwise stated. All viscosity measurements were carried out in duplicate, and values averaged. Error bars represent the standard deviation between the replicates.