These results indicate the feasibility of achieving uniform coverage and, notably, uniform chemical modification using the "grafting to" method, at least down to the resolution of an AFM (a few nm in lateral resolution), despite the lower grafting density (𝜎) characteristic of the "grafting to" approach. Further estimation of the value of 𝜎 will be discussed later in the manuscript. While both carboxylic acid (-COOH) and hydroxyl (-OH) functionalities have been reported in literature as functional groups for grafting polymers to the native oxide layer of Si substrates under melt grafting conditions, 19, 46-52 here we found that under the same melt grafting conditions, i.e., annealing polypeptoid thin films spin coated on Si substrates at 180 °C for 30 min, only the -OH functionalized polypeptoids efficiently graft onto Si substrates, while the -COOH functionalized polypeptoids only form discrete aggregates on the equivalently treated substrates (Supporting Information, Figure ). Similar trends in grafting efficiency between PS-OH and PS-COOH,