A Review on Nanocellulose for Biobased Paint Formulations: A Sustainable Additive for Enhanced Corrosion Resistance

Conventional paint and coating often rely on toxic additives to achieve protection, including corrosion inhibition. However, these toxic additives pose major disadvantages related to environmental impact and toxicity. As the need for paint with enhanced overall performance and the development of sustainable strategies increase, nanocellulose, a biodegradable and renewable biomaterial, has emerged as a promosing additive. However, its hydrophilic properties hinder the dispersion within hydrophobic host polymers, frequently leading to aggregation that diminishes coating performance, particularly in corrosion‐resistant applications. Furthermore, nanocellulose's efficacy as a dispersing agent is diminished by its tendency to self‐aggregate at high concentrations. Moreover, challenges also remain regarding its scalability and cost‐effectiveness, particularly in large‐scale industrial manufacturing. Hence, this review aims to address these gaps by evaluating how surface modification can unlock the potential of nanocellulose for high‐performance bio‐based paint formulations. This review introduces the primary types and typical examples of nanocellulose in various dimensions, followed by an overview of current surface modifications strategies that enhance dispersibility, hydrophobicity, adhesion, self‐cleaning behaviour, and corrosion protection. In addition, this review covers recent scientific research on the multifunctional properties of paint incorporating unmodified and modified nanocellulose, with emphasis on mechanisms such as microcavity filling and tortuous diffusion barriers that contribute to improved corrosion resistance. Ultimately, this review presents a critical assessment of the remaining challenges, trends, and future perspectives, particularly in the areas of regulatory acceptance, scalable production, and economic feasibility.