Reactive and non-reactive compatibilization of polyethylene terephthalate glycol/thermoplastic polyurethane (PETG/TPU) blends for 3D/4D printing applications

In recent years, research on 3D and 4D printing has experienced rapid growth due to its vast potential for applications across multiple fields. Polymer blends of polyethylene terephthalate glycol (PETG) and thermoplastic polyurethane (TPU) have emerged as promising candidates for such applications. PETG offers good shape fixity but limited recovery capability, whereas TPU, as an elastomer, provides excellent shape recovery but poor fixity. Therefore, blending PETG with TPU presents a strategic approach to balancing these complementary shape memory characteristics. However, the immiscibility between PETG and TPU can limit the overall performance of their blends. To address this, compatibilizers can be employed to enhance interfacial adhesion and stabilize blend morphology. This study explores reactive and non-reactive compatibilization strategies for PETG and polycaprolactone-based TPU blends, aiming for 3D/4D printing applications. Three compatibilizers were evaluated: styrene-ethylene-butylene-styrene (SEBS), maleic anhydride-functionalized SEBS (SEBS-MA), and ethylene-glycidyl methacrylate (E-GMA). The blends were prepared via melt blending, extruded into filaments, and used to print test specimens. Comprehensive analyses were conducted to assess shape memory behavior, as well as chemical, rheological, morphological, and mechanical properties. The results demonstrated that all compatibilizers enhanced both the shape memory effect and mechanical performance of PETG/TPU blends. Notably, reactive compatibilization using E-GMA yielded the most significant improvements. Compared to uncompatibilized blends, the E-GMA system exhibited a ∼ 12.7 % increase in shape recovery, along with enhancements in mechanical properties: Young's modulus increased by ∼20 %, tensile strength by ∼37 %, elongation at break by ∼550 %, and impact strength by ∼70 %, reaching values exceeding 650 J/m, characteristic of supertough polymers. These improvements were attributed to reduced interfacial tension, enhanced phase adhesion, and improved morphological stability in the compatibilized blends, resulting in superior printing quality. Overall, this study highlights the effectiveness of compatibilization, particularly reactive compatibilization, in improving the performance of immiscible polymer blends for advanced 3D/4D printing applications, paving the way for the development of high-performance material systems.