Surface Functionalization of Polyimide Films via Chloromethylation and Surface-Initiated Atom Transfer Radical Polymerization

Abstract

The ability to manipulate, in a well-controlled manner, the surface properties of polyimide (PI) films, without altering the substrate properties, is crucial to the applications of this polymer, which is important to the microelectronics industry. In this work, a simple one-step method for the chloromethylation of PI was first developed. It was demonstrated that the chloromethylated PI film surface (PI−Cl surface) provided effective macroinitiators for surface-initiated atom transfer radical polymerization (ATRP). Functional polymer brushes of 2,3,4,5,6-pentafluorostyrene (PFS), 2,2,2-trifluoroethyl methacrylate (TFEMA), and 2-hydroxyethyl methacrylate (HEMA) were prepared via surface-initiated ATRP from the PI−Cl surfaces. Atomic force microscopy (AFM) images revealed that the surface-initiated ATRP had proceeded uniformly on the PI−Cl surfaces to produce a dense and molecularly flat surface coverage. The dormant chain ends of the grafted PFS polymer (P(PFS)), HEMA polymer (P(HEMA)), and TFEMA polymer (P(TFEMA)) on the PI films could be reactivated for the consecutive surface-initiated ATRP to produce the corresponding PI films with surface-functionalized P(PFS)−b-P(HEMA), P(TFEMA)−b-P(HEMA), and P(HEMA)−b-P(TFEMA) diblock copolymer brushes.