SI-ATRP Polymer-Functionalized Graphene Oxide for Water Vapor Separation

Abstract

Graphene oxide is functionalized with poly(2-diethylaminoethyl) methacrylate (PDEAEMA), and the resulting material is used as a selective layer of a thin-film composite membrane (TFCM). The polymer synthesis is carried out by surface-initiated atom transfer radical polymerization (SI-ATRP) from bulk and also from single-layer graphene oxide (GO). The polymer brushes synthesized by the “grafting from” method are characterized by size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and TGA-FTIR. The TFCMs are prepared by the deposition of the selective layer from a stable polymer solution. The molecular weight of the polymer is sufficiently high to obtain a continuous defect-free layer on a porous support. The thickness of the selective layer is ≈400 nm, as found in morphological investigations by scanning electron microscopy (SEM). The obtained membranes are utilized for gas and water vapor transport experiments in a wide temperature range. The water vapor permeability coefficient of the investigated materials is up to 4500 Barrer; this value increases threefold upon quaterization of the amine. The high permeance and selectivity for water vapor make this type of thin-film membranes a potential candidate for membrane distillation.