Observations on spatial specificity in the modification of porous graphene layers

Abstract

Self-initiated photografting and photopolymerization (SIPGP) is a simple one-step polymerization process that can yield dense polymer layers on various surfaces, including pristine graphene. This process, however, has so far not been managed to be site selective. Herein, SIPGP is used to selectively functionalize the edges of pores in chemical vapor-deposited porous graphene sheets. The pore edges formed during the graphene fabrication serve as directing reactive sites for the functionalization process. By polymerizing styrene monomers from the pore edges using a radical-mediated process, polymer chains are preferentially grafted along and from the pore edges of the graphene. The spatial selectivity of the process is unambiguously demonstrated by the presence of a polymer rim around the pores in the atomic force microscopy data. The height of these polymer rims and the pore dimensions are measured, demonstrating the tunability of these characteristics by changing the reaction conditions (varying polymerization time from 0 to 24 h). The precise selectivity and controllability of the SIPGP process for the pore edges are potentially interesting for using porous graphene as functional membranes in different technological applications such as Per- and Polyfluoroalkyl substances (PFAs) -free waterproof membrane or state-of-the-art membranes for water desalination.