Hydrogen Bond Cross-Linked Montmorillonite-Enhanced Biodegradable Carboxymethyl Cellulose/Guar Gum Composite Films

Carboxymethyl cellulose (CMC) has attracted considerable interest in research due to its exceptional film-forming properties and compatibility with biological systems. However, CMC films still suffer from mechanical brittleness and structural instability due to the rigid structure and many hydroxyl groups in practical applications. Herein, a nanocomposite film is reported, synthesized via inserting layered montmorillonite (MMT) into a CMC and guar gum (GG) hydrogen bond networks. Incorporating MMT with a high aspect ratio increases the number of hydrogen bond cross-linking sites among constituents, thereby enhancing the mechanical strength and toughness of nanocomposite films. The resulting CMC/GG10/MMT6 films show flexibility (elongation at break 83.5 ± 4.35%), high tensile strength (53.5 ± 1.10 MPa), and high toughness (32.16 ± 1.04 MJ/m3). These films also integrate hydrophobic (up to 84.78°) and high-temperature resistance (50% degradation temperature up to 304 °C) properties to adapt to complex practical application environments. Moreover, they exhibit excellent ultraviolet shielding performance under a wide wavelength range (200–320 nm). Soil burial experiments showed that all the films could be assimilated into the soil within about 9 days. This approach offers a simple and promising route for producing biodegradable CMC-based films for food packaging.