Thermosensitive graphene nanocomposites formed using pyrene‐terminal polymers made by RAFT polymerization

Abstract

AbstractThermosensitive graphene‐polymer composites have been prepared by attaching poly(N‐isopropylacrylamide) (PNIPAAm) onto the basal plane of graphene sheets via π‐π stacking. Pyrene‐terminated PNIPAAm was synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization via a pyrene‐functional RAFT agent. Aqueous solutions of the graphene‐polymer composites were stable and thermosensitive. The lower critical solution temperature (LCST) of pyrene‐terminated PNIPAAm was measured to be 33 °C. When the pyrene‐functional polymer was attached to graphene the resultant composites were also thermosensitive in aqueous solutions exhibiting a reversible suspension behavior at 24 °C. Atomic force microscopy (AFM) analysis revealed that the thickness of a graphene‐PNIPAAm (Mn: 10,000 and PDI: 1.1) sheet was ∼5.0 nm. The surface coverage of polymer chains on the graphene basal plane was calculated to be 7.2 × 10−11 mol cm−2. The graphene‐PNIPAAm composite material was successfully characterized using X‐ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR‐IR) spectroscopy, and thermogravimetric analysis (TGA). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 425–433, 2010