Radiation-induced graft polymerization of N-isopropyl acrylamide onto microcrystalline cellulose: Assessing the efficiency of the peroxidation method

Abstract

This article reports on the development of an experimental protocol based on the radiation-induced graft polymerization of a temperature-responsive polymer onto cellulose (MCC). MCC was selected as a model substrate, in view of modifying cellulose nanocrystals (CNCs). Two different grafting methods, by pre-irradiation or simultaneous procedure, were performed to assess their efficiency and identify key experimental steps. The Fenton reaction was successfully applied to radiation-peroxidized MCC. The effects of radiation dose, reaction temperature, monomer concentration and reaction time were studied in various combinations to control the polymerization of N-isopropyl acrylamide (NIPAM). The amount of poly(NIPAM) grafted on MCC was determined by elemental analysis. Grafted MCC samples were characterized by infrared spectroscopy, thermogravimetry, scanning electron microscopy and X-ray diffraction to compare their features with the unmodified substrate. This experimental approach was then applied to CNCs. The grafting and purification protocols for the modified CNCs were adapted accordingly. Preliminary characterization shows the presence of the poly(NIPAM) grafts onto the CNCs and evidences the temperature-reponsiveness of the obtained material.