Influence of Botanical Origin on the Optical, Surface, and Nanomechanical Properties of Nanocellulose‐Based Films: A Comparative Study

ABSTRACT Although the influence of botanical origin on nanocellulose properties is well recognized, an integrated multiscale framework linking chemical composition, fractal surface descriptors, and nanomechanical behavior under unified processing conditions remains unexplored for nanocellulose‐based films. This work examines the effect of botanical origin on the multiscale properties of nanocellulose films produced under a standardized protocol from seven sources, including the first report of babaçu‐ and sisal‐derived films. Natural‐fiber films (açaí, babaçu, cactus, coffea) exhibit strong UV‐shielding (> 98% UVA blocking) but reduced transparency, whereas commercial eucalyptus and pinus pulps yield transparent films with limited UV protection. These optical differences, consistent with variations in lignin‐derived chromophores, are supported by colorimetry and FTIR analysis. Atomic force microscopy reveals nanoscale surface organizations, with eucalyptus and sisal showing higher spatial complexity (Df > 2.2), while force spectroscopy demonstrates that deformation behavior depends not only on intrinsic stiffness but also on adhesion‐mediated responses. To the best of our knowledge, this is the first study to apply fractal surface parameters (Df, succolarity, and lacunarity) to correlate nanotopography with nanomechanical behavior in nanocellulose‐based films. Together, results identify botanical source a key parameter and provide a framework for selecting feedstocks for applications such as UV‐protective coatings, transparent substrates, or composites.