چكيده لاتين
Coatings are recognized as one of the most effective solutions for protecting surfaces against environmental factors, corrosion, and wear, significantly contributing to the durability and performance enhancement of materials. Polymer coatings have gained a special position in various industries due to their lightweight, ease of processing, good adhesion to substrates, and the ability to adjust their chemical structure. However, conventional polymer coatings, which are primarily produced from petroleum sources, face serious limitations due to dependence on fossil resources and environmental issues. Therefore, the development of bio-based coatings derived from natural polymers such as starch, chitosan, alginate, vegetable oils, and polyphenols has gained attention as sustainable alternatives. The inherent weaknesses of natural materials, such as low mechanical properties, sensitivity to moisture, and limited thermal stability, necessitate structural modification and improvement. Strategies such as chemical crosslinking to enhance thermal and mechanical resistance, adding nanomaterials to strengthen properties and create stronger interactions, modifying starch to reduce hydrophilicity and improve processability, and using water-based polyurethanes with suitable polarity to increase compatibility between the matrix and fillers are considered effective approaches to address these challenges. Polyurethanes have gained a special place due to their unique combination of mechanical properties, flexibility, chemical resistance, and barrier properties. In this context, the development of water-based polyurethanes as a sustainable and environmentally friendly alternative, along with innovative technologies such as ultraviolet radiation curing, which creates a fast, low-energy, and pollution-free process, has opened new horizons in the design of green coatings. In this research, UV-cured water-based polyurethane nanocomposite coatings were synthesized using isophorone diisocyanate, polytetramethylene ether glycol, dimethylol propanoic acid, and hydroxyethyl methacrylate. To simultaneously enhance mechanical and thermal properties, two reinforcing components, including glycidyl methacrylate-modified starch and phytic acid-intercalated layered double hydroxide nanostructures, were added to the system. The surface modification of LDH with phytic acid not only facilitated uniform dispersion in the matrix but also contributed to increased thermal stability by creating a flame-retardant effect and preventing heat transfer. The results of mechanical tests showed that the optimal sample had a tensile strength of 3.46 MPa and an elongation of 410%, indicating the simultaneous preservation of strength and flexibility. Additionally, TGA analysis showed an increase in char yield up to 43.12% and improved thermal stability, confirming the role of interfacial bonds and phase homogeneity. Overall, this synergistic effect between the modified biopolymer and the mineral nanofiller led to the production of a multifunctional, stable, and environmentally friendly coating for advanced industrial applications such as automotive, electronics, and packaging.
