Fig. 1: Potentiometric titration experiments in the presence of polymer additives.

a pH dependency of the scale factor (crystallization time relative to reference) for experiments containing 10 mg/L PAsp (red) and PGlu (blue). b Amount of NaOH added in titration experiments at pH 9.0 containing 10 mg/L polymer. The dotted lines visualize the slope of added NaOH in the prenucleation regime close to nucleation. In experiments with polymer, the extent of NaOH addition was significantly lower (see inset for easier comparison of slopes). c Development of molar amount of bound CO₃²⁻ per added Ca²⁺ in the prenucleation regime for experiments containing 0.1 g/L (PAsp and PGlu) or 0.01 g/L (PAA) polymer at pH 9.8. Values are calculated from the Ca-ISE (green) by assuming a 1:1 Ca²⁺:CO₃²⁻ binding ratio and from the NaOH addition (black) by calculating the amount of bound CO₃^2- from changes in buffer equilibria. d From the values shown in (c), the proportion of bicarbonate binding relative to the total amount of bound carbonate species (CO₃²⁻ + HCO₃⁻) can be calculated (black). Error bars represent ±1 − σ-standard deviation. The scale factors for each experiment are also shown (orange bars). The calculations are described in detail in Section 2 in the Supplementary Information.