Nb(v), Ta(v), and V(iv) catalyst-driven development of temperature-responsive self-healing materials based on methyl methacrylate

Abstract

This study fills an important gap in the use of group V cation complexes – Nb(V), Ta(V), V(IV) – as versatile catalysts that can be used both in the polymerisation of olefins and in the synthesis of MMA-based materials that exhibit temperature-responsive properties and self-healing capabilities. This area has so far remained insufficiently explored. The work shows clear structure–property relationships of the materials and highlights their potential for green applications. This work introduces newly developed crystalline coordination compounds of Nb(V), Ta(V), and V(IV), synthesized with ligands such as 2-phenylpyridine, 4-phenylpyridine, and dimethylformamide (DMF). These complexes were explored as catalysts in both ethylene polymerization and its copolymerization with 1-octene, in addition to their role in forming temperature-responsive, self-healing materials based on methyl methacrylate (MMA). The catalysts demonstrated notable versatility, effectively enabling the synthesis of traditional polyolefins as well as advanced MMA-derived polymers with adaptive features. Rheological and mechanical testing showed that both the choice of catalyst and the concentration of MMA significantly impacted key material properties, including viscosity, shear stress, hardness, and healing capability. Particularly impressive were the V(IV)-based catalysts, which enabled rapid self-healing. For instance, the V-PE-50MMA composition achieved full structural recovery within just 15 minutes at 35 °C. Microscopic analysis revealed a transformation in material structure—from dense to porous forms—as MMA content increased, which was linked to stronger molecular interactions.