For ATRP of PSPMA, ascorbic acid was replaced by CuCl (29.7 mg, 0.3 mmol). The 24-multiwell plate was placed inside of a in-house-built sealed chamber and purged with argon for 10 min. 1 mL of polymerisation solution was injected and the reaction was stopped at different time points through dilution with deionised water. Brush-functionalised substrates were washed with ethanol, dried with a N2 stream, and characterised by ellipsometry.