Kinetic Modeling of Surface‐Initiated Atom Transfer Radical Polymerization

Abstract A kinetic model has been developed using the method of moment for surface‐initiated atom transfer radical polymerization (s‐ATRP) from flat solid surfaces based on a moving boundary physical model. The model is verified with the experimental data of 2‐methacryloyloxyethyl phosphorylcholine from silicon wafer, which were carried out by either adding free initiator (Method I) or excess deactivator (Method II) to the solution. It is shown through the modeling that Method II gives better control over polymer molecular weight and thicker graft layer under similar conditions than Method I. A new mechanism is proposed for the radical termination based on the fact that the rapid activation/deactivation cycle reactions facilitate “migration” of radical centers on the surface. The rate constant of “migration termination” is thus catalyst concentration dependent with higher catalyst concentration resulting in higher termination. Lowering catalyst concentration suppressed migration termination that could improve the control and livingness of s‐ATRP. However, there exists a catalyst concentration for the optimal control performance. magnified image