Fig. 5. (a) Comparison of the long-term colloidal stability of the MXene-g-poly(AMPS-co-AA) (upper) and MXene-g-poly(DMAPS-co-AA) (lower) in an API brine. The d_H of the MXene-g-poly(AMPS-co-AA) and MXene-g-poly(DMAPS-co-AA) within 0.1 M ≤ C_s ≤ 1.0 M, normalized by the d_H at C_s = 0.1 M in the (b) NaCl and (c) CaCl₂ solutions.