Carboxymethyl cellulose/layered double hydroxide nanocomposite films with high barrier property and transparency

Abstract

Petroleum-based general-purpose polymers, like polyethylene and polypropylene, have become the most economical and practical solution for packaging applications due to their characteristics, such as low cost, excellent optical, mechanical, and barrier properties. However, the significant environmental issues associated with the extensive use of these synthetic polymers have prompted searches for new sustainable alternatives. In pursuit of a carbon–neutral economy, the aim of this work is to develop a nanocomposite film combining high barrier property and transparency, suitable for packaging purpose, utilizing commercial cellulose derivatives (carboxymethyl cellulose, CMC) and 2D non-toxic layered double hydroxide nanosheets (LDH-NSs). Employing a simple, eco-friendly method, the nanocomposite films (CMC/LDH-NS) are fabricated by mixing and casting a mixed suspension from a CMC solution and an LDH-NS suspension, facilitated by a non-toxic exfoliation method in an aqueous amino acid solution. The effects of different ratios of LDH-NS on the barrier properties and transparency of the nanocomposite films are studied, along with the related mechanism through comprehensive analysis of micromorphology, X-ray diffraction, and Fourier-transform infrared spectroscopy. The CMC/LDH-NS films present a remarkable 252-fold increase of oxygen barrier and a 51% improvement in water vapor barrier performance compared to the pure CMC film. Moreover, the nanocomposite films maintain high light transmittance, with values exceeding 80% at 600 nm, even at a 50% LDH-NS:CMC ratio. These outstanding attributes underscore the potential of CMC/LDH-NS nanocomposite films for broad application in food and pharmaceutical packaging, as well as in electronic encapsulation, marking a significant step forward in the development of sustainable packaging solutions.