The present work seeks to determine the impact of weight percentage (wt%) of grafted starch nanocrystals (g-SNCs) on the oxygen and water vapour permeability of poly (lactic acid), PLA. Changes in the oxygen and water vapour permeability of PLA due to changes in PLA’s crystalline structures and lamellar thickness were quantified. To this end, 3, 5, and 7 wt% of g-SNC nanoparticles were blended with PLA using the solvent casting method in order to study impact of g-SNC nanoparticles on crystallization behaviour, long spacing period, melting behavior, and oxygen and water barrier properties of PLA nanocomposites. This was achieved by wide-angle X-ray diffraction (WAXD), small-angle X-ray diffraction (SAXD), differential scanning calorimetry (DSC), and oxygen and water vapour permeability machine. The results of the WAXD and SAXD analysis show that the addition of 5 wt% g-SNC in PLA induces $\alpha$ crystal structure at a lower crystallization time, while it significantly increases the $\alpha$ crystal thickness of PLA, in comparison to neat PLA. However, when g-SNC concentrations were altered (i.e., 3 or 7 wt%), the crystallization time was found to increase due to the thermodynamic barrier of crystallization. Finally, the oxygen and water vapour permeability of PLA/SNC-g-LA (5 wt%) nanocomposite film were found to be reduced by ∼70% and $~$50%, respectively, when compared to the neat PLA film. This can lead to the development of PLA nanocomposites with high potential for applications in food packaging.

Organometallic coupling agents play a crucial role in polymer blends and composites by enhancing the compatibility between different polymers or improving interfacial adhesion between polymers and reinforcement agents or fillers. These agents facilitate chemical bonding, improving mechanical properties, dispersibility, and moisture resistance. While conventional coupling agents, such as silanes, are widely used across various applications, they present limitations, including susceptibility to hydrolytic degradation in aqueous environments and reduced bonding efficiency with non-silica or non-hydroxyl-bearing compounds. This poses challenges in developing composites with long-term hydrolytic stability, a key objective in polymer materials research. Hence, pursuing hydrolytically stable composites remains critical in polymer materials research. In contrast, organometallic compounds such as titanate coupling agents improve the bonding between inorganic materials—such as carbon, graphite, calcium carbonate (CaCO ₃ ), hydroxyapatite, and metal oxides—and polymer matrices. While the effect of these coupling agents on the physical and mechanical properties of dental prostheses have been thoroughly reviewed, few attempts have addressed these coupling agents’ applications in polymer compounds/composites. This paper aims to review the application of organometallic compounds such as titanate and zirconate coupling agents in polymer blends and composites to highlight and identify gaps in the earlier research work and provide resourceful data for future research. The review offers insights and valuable data to advance the knowledge of polymer composites, particularly in tailoring an enhanced interfacial bonding for long-term performance under harsh environmental conditions.