Nanocomposites by Surface-Initiated Living Cationic Polymerization of 2-Oxazolines on Functionalized Gold Nanoparticles

Abstract

End-functionalized 3D self-assembled monolayers (SAMs) on gold nanoparticles were used to initiate the living cationic ring-opening polymerization reaction directly on gold nanoparticle surfaces (“grafting-from technique”). In this manner, dense polymer brushes were prepared in a “one-pot multistep” reaction. ER FTIR spectroscopy confirms the successful polymerization reaction as well as the introduction of a terminal functional group. The resulting gold/polymer nanocomposite was very stable. The combination of a “grafting-from reaction” resulting in polymer “brush-type” shells of linear macromolecules and the introduction of a terminal mesogen by means of a quantitative termination reaction resulted in an amphiphilic core−shell material with a well-defined hydrophilic/lipophilic balance (HLB). Ex-situ kinetic studies of the polymerization of 2-phenyl-2-oxazoline using FTIR spectroscopy and MALDI TOF mass spectrometry resulted in a linear relationship between the reaction time and degree of polymerization of the grafted polymer. This as well as the successful end-functionalization by termination with secondary amines corroborates our view of a well-defined living polymerization mechanism.