Surface Modification of Polypropylene with Primary Amines by Acrylamide Radiation Grafting and Hofmann's Transposition Reaction

Abstract Polypropylene (PP) film surface is modified with primary amines by means of gamma radiation to graft acrylamide (AAm) using the pre‐irradiation oxidative method at a dose of 50 kGy, a monomer concentration of 13%, and a temperature of 60 °C for 6 h, followed by Hofmann rearrangement to reduce the primary amide groups of the grafted polymer (PP‐g‐AAm) to obtain vinylamine (VAm) groups (PP‐g‐VAm). The films are characterized using infrared spectroscopy before and after the reduction reaction; the hydrophilicity is studied using the contact angle; the thermal stability of the films are observed using TGA and DSC; and the surface morphology is determined using SEM. The presence of primary amines and the corresponding decrease in C=O and O=C‐NH 2 groups due to reduction reaction, are confirmed using X‐ray photoelectron spectroscopy. In addition, the surface primary amines are quantified using a colorimetric method that calculated the amount as 1.9 + 0.1 nmol/mm 2 .