Functionalization of Nitrocellulose Film by AB-Type Click Polymerization: Methods and Property Enhancements

Nitrocellulose (NC), predominantly used in propellants and purifying membranes, has further gained attention recently because of its application potential in flexible solar cells, molecular electronic devices, biochemical processes, and leather coatings. For the diversification of application areas of nitrocellulose-based materials, some of the inherent properties like flexibility, transparency, hydrophobicity, stability, heat of denitration, etc., require improvements. As presented in this paper, most of those properties were found to be substantially enhanced after the functionalization of nitrocellulose surfaces by a unique AB-type click polymerization, attributed to changes in chemical functionality, crystallinity, morphology, etc., as observed from X-ray diffraction (XRD), field-emission scanning electron microscopy, atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS) analyses. Unlike conventional AABB-type click polymerization, herein, both azide and alkyne functional groups have been incorporated in the same monomer for better efficacy, where AB-type click polymerization took place in the presence of azide-functionalized nitrocellulose. This is a typical graft-through approach, where polymerization took place both in solution as well as on surfaces, providing flexibility of characterization in both states for the clear-cut evidence of the success of this typical polymerization as well as immobilization, as studied by solution-state as well as solid-state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The material was used as a hydrophobic/superhydrophobic coating for leather surfaces.