The equilibrium constant (K-ATRP) is a key factor for ensuring a successful atom transfer radical polymerization (ATRP), which guarantees a controlled process with predictable product properties. In this work, the effect of initiator type (i.e., micromolecular, macromolecular, and immobilized initiator) on the ATRP kinetics was studied through a developed mathematical model. It was validated thoroughly via experiments using fluorinated monomer (2,2,3,3,4,4,4-heptafluorobutyl methacrylate) as model component. The results show that the activity and deactivity of the copper(I) chlorine/1,1,4,7,7-pentamethyldiethylenetriamine ((CuCl)-Cl-I/PMDETA) heterogeneous catalytic complex is the highest for ethyl 2-bromoisobutyrate (Eib-Br), lower for bromo-poly(styrene) (PS-Br), and the lowest for bromo-aminopropyl functionalized SiO2 (SiO2-APTS-Br). The initiation system of Eib-Br with (CuCl)-Cl-I/4,4'-dinonyl-2,2'-bipyridyl (dNbpy) has relatively lower activating ability, but the polymerization keeps controllable by its higher deactivating ability. In addition, this homogeneous catalytic system ((CuCl)-Cl-I/dNbpy) is facile for further implementing the developed model to guide for the preparation of fluorinated gradient copolymers by semi-batch ATRP. (C) 2014 Wiley Periodicals, Inc.