Surface-initiated ring opening polymerization of N-carboxy anhydride of benzyl-l-glutamate monomers on soft flexible substrates

Abstract

The potential of pulsed plasma deposited polyallylamine (PAA) adlayer has been successfully demonstrated for fabrication of polypeptide brushes functionalized soft flexible polymeric surfaces. Polymeric substrates functionalized with the plasma deposition PAA adlayer resulted in polymeric surfaces functionalized with amino groups, which are the suitable initiating moieties for ring-opening polymerization (ROP) of N-carboxy anhydride of benzyl-l-glutamate (NCA-BLG) monomer. Poly(γ-benzyl-l-glutamate) (PBLG) brushes were grown on PAA functionalized polypropylene (PP), and polytetrafluoroethylene (PTFE) polymeric substrates. These substrates were intentionally chosen for their inert chemical nature towards most wet chemical surface modification reactions. Surface grafted thin films of poly(γ-benzyl-l-glutamate) PBLG on both the PP and PTFE polymeric substrates yielded high density PBLG brushes. PBLG chain orientation, secondary structure and grafting density were characterized by infra-red spectroscopy. The synthesis of PBLG brushes on a flexible polymeric substrate is unprecedented and technologically important, since PBLG possess good electro-optical activity. Analysis of brush layers by Attenuated Total Reflectance Infra-Red (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) as well as atomic force microscopy (AFM) fully corroborated the success of the plasma activated soft surface grafting approach.