In agreement with the literature, the growth of PSPMA brushes from dense and sparse monolayers of initiators (monolayers composed of 100% and 5% of silane ATRP initiators, respectively) was found to be relatively linear, with a steady increase in thicknesses to 60 and 40 nm over 120 min of polymerisation, respectively (Figures and). Interestingly, the thickness of PSPMA brushes generated via ARGET, at both densities, was found to be significantly higher, although a clear reduction in brush growth was observed after 60 min. Although such thicknesses are in agreement with the growth of other hydrophilic brushes by ARGET, including POEGMA and PDEAEMA , such enhancement in rate is not typically reported, although direct quantitative comparisons between SI-ARGET and SI-ATRP have not been systematic. This enhanced kinetics was observed on brushes grown from both high and low density initiators, with comparable rate accelerations (just under double the thickness achieved by ARGET compared to ATRP). Comparable growth kinetics were observed for brushes generated from gold substrates coated with ATRP-thiol initiators (Supplementary Figure ), although with less reproducibility at later time points, perhaps resulting from slight variations in oxygen exposure when brushes were generated in separate batches (no precaution was taken to exclude oxygen during polymerisation). Therefore, ARGET appears as an ideal polymerisation system to carry out PSPMA brush growth from surfaces in deoxygenated solutions, but without elimination of atmospheric oxygen (brush growth was carried out in multi-well plates in the case of ARGET, see methods).