Valorization of seaweed biomass into silica‐reinforced biopolymer films: structure–property relationships and interfacial mechanisms

The valorization of marine biomass into high‐value bioproducts is crucial for reducing reliance on petroleum‐based plastics while supporting circular bioeconomy strategies. In this study, seaweed ( Kappaphycus alvarezii ) biomass was converted into biodegradable biopolymer films and reinforced with commercial silica nanoparticles (SNPs) to enhance structural integrity and functional performance. Nanocomposite films containing 0–7 wt% SNP were fabricated via solution casting and systematically investigated using Fourier‐transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. Spectroscopic analyses confirmed SiOSi contributions and strong polymer–silica interfacial interactions, while XRD results showed that SNP addition maintained the semi‐crystalline characteristics of the seaweed matrix with subtle structural refinement. Morphological assessments revealed that 3–5 wt% SNP loadings produced dense, uniform surfaces and improved microstructural organization owing to effective filler dispersion, whereas higher loadings resulted in particle agglomeration and interfacial defects. The study demonstrates that controlled incorporation of SNPs can tailor microstructure, interfacial bonding, and stability in seaweed‐derived biopolymers, offering valuable insights for developing renewable, biodegradable nanocomposite materials within sustainable biorefining and bio‐product applications.