Fabrication of Cationic Poly(vinyl alcohol) Films Cross-Linked Using Copolymers Containing Quaternary Ammonium Cations, Benzoxaborole, and Carboxy Groups

Carboxymethyl cellulose/poly(vinyl alcohol) blended films reinforced by buckypapers of carbon nanotubes and 2D material (MoS2): Enhancing mechanical strength, toughness, and barrier properties

Plastic waste is one cause of climate change. To solve this problem, packaging films are increasingly produced from biodegradable polymers. Eco-friendly carboxymethyl cellulose and its blends have been developed for such a solution. Herein, a unique strategy is demonstrated to improve the mechanical and barrier properties of carboxymethyl cellulose/poly(vinyl alcohol) (CMC/PVA) blended films for the packaging of nonfood dried products. The blended films were impregnated with buckypapers containing different combinations of multiwalled carbon nanotubes, two-dimensional molybdenum disulfide (2D MoS₂) nanoplatelets, and helical carbon nanotubes (HCNTs). Compared to the blend, the polymer composite films exhibit significant increases in tensile strength (~105 %, from 25.53 to 52.41 MPa), Young's modulus (~297 %, from 155.48 to 617.48 MPa), and toughness (~46 %, from 6.69 to 9.75 MJ m^-3). Polymer composite films containing HCNTs in buckypapers offer the highest toughness. For barrier properties, the polymer composite films are opaque. The water vapor transmission rate of the blended films decreases (~52 %, from 13.09 to 6.25 g h^-1 m^-2). Moreover, the maximum thermal-degradation temperature of the blend rises from 296 to 301 °C, especially for the polymer composite films with buckypapers containing MoS₂ nanosheets that contribute to the barrier effect for both water vapor and thermal-decomposition gas molecules.

Cicada-Wing-Inspired Nanopillar Hydrogels Consisting of Poly(vinyl alcohol) and Poly(methacrylic acid) for Capturing Bacteria through Their Flexibility and Wide Range of Motion

The human race has learned about countering bacterial infection from other living organisms. In this study, cicada-wing-inspired hydrophilic nanopillars were prepared using commercially available porous alumina templates without the use of specialized equipment and additional materials. Hydrophilic polymers of poly(vinyl alcohol) (PVA) and poly(methacrylic acid) (poly(MAAc)) were used to construct these nanopillars. The water-insoluble nanopillars formed by thermal cross-linking between the hydroxy and carboxy groups were highly flexible, with no significant structural disruption being observed on tilting them. The nanopillars captured Gram-negative and Gram-positive bacteria, despite their negatively charged surface leading an electrostatic repulsion with bacteria. The wing of the cicada has evolved to remain dry and maintain its lightweight. The water-containing cicada-wing structure may be an unknown encounter for bacteria and, thus, may become a countermeasure against the ever-changing bacteria.