Surface initiated ring-opening polymerization of l-proline N-carboxy anhydride from single and multi walled carbon nanotubes

Ring-opening surface initiated polymerization of l-proline N-carboxyanhydride was performed from amine functionalized single (SWNTs) and multi walled carbon nanotubes (MWNTs). The primary amines were grafted on the surfaces via a well-studied Diels-Alder cycloaddition. The initiator attachment helped the debundling of carbon nanotubes as shown by atomic force microscopy (AFM) studies where only small aggregates were observed. Thermogravimetric analysis revealed high wt% of grafted polyproline on the carbon nanotubes surface after the ring-opening polymerization. AFM studies showed a rather uniform layer of grafted polyproline from both MWNTs and SWNTs. The grafting of PLP on the surface was also verified by FTIR and Raman spectroscopy as well as ¹H NMR in CDCl₃/d-TFA. The polyproline grafted carbon nanotubes (CNTs) were readily dissolved in organic solvents in contrast to the insoluble pristine and amine-functionalized CNTs.