Shape-memory polymers (SMPs) possess unique properties that respond to external stimuli. The current review discusses types of SMPs, fabrication methods, and the characterization of their mechanical, thermal, and shape recovery properties. Research suggests that SMP composites, when infused with fillers, demonstrate enhanced mechanical and thermal characteristics. On the other hand, blends, particularly incorporating polylactic acid (PLA), exhibit the most efficient shape recovery. Furthermore, the crosslinking density in polymer blends impacts the shape recovery force, showcasing a correlation between energy storage capacity and shape recovery force in SMP networks. Overall, SMP blends show promising mechanical, thermal, and shape recovery features, rendering them advantageous for applications of artificial muscles, soft actuators, and biomedical devices. This review also discusses the future prospectives of SMP for robust applications.

This research presents an experimental investigation into the mechanical, thermal, and shape memory behavior of a thermos-responsive polyurethane (PU) reinforced with 0–1.0 wt % of MXene (Ti₃C₂T_x) nanofiller. The PU/MXene nanocomposites were fabricated using sonication and injection molding route. The 0.5 wt % PU/MXene nanocomposite showed the optimum mechanical properties i.e. tensile modulus, tensile strength, and hardness value, which are improved by 22, 281, and 19 %, respectively, compared to pure PU. The improvement is observed in melting temperature (T_m), the heat of melting (h_m), crystallization temperature (T_c), and the heat of crystallization (h_c) results. The percentage of crystallinity revealed enhancements of 6 %, 18 %, 24 %, and 34 % for 0.1, 0.2, 0.3, and 0.5 wt % PU/MXene samples respectively compared to pure PU. The findings from the shape recovery experiments demonstrated that the inclusion of MXene has no impact on both the shape fixity and shape recovery performance. The PU/MXene nanocomposite with improved mechanical and thermal properties can find potential applications in robotics actuators, medical devices, sensors, etc.

This study investigates the fabrication and characterization of heat-responsive PLA/PU/MXene shape memory polymer blend nanocomposites with varying PLA content (10, 20, 30, and 50%) and a fixed MXene content of 0.5 wt.%. The results indicate significant improvements in mechanical properties, with the 50% PLA/PU/MXene blend showing a 300% increase in ultimate tensile strength and a 90% decrease in % elongation compared to pure PU. Additionally, the 50% blend exhibited a 400% increase in flexural strength. Microstructural analysis revealed dispersed pores and sea–island morphology in pure PU and the 50% PLA/PU/MXene blend. Thermal analysis using DSC showed an increase in crystallinity from 33% (pure PU) to 45% for the 50% PLA/PU/MXene blend, indicating enhanced crystalline domains due to the semi-crystalline nature of PLA and MXene’s influence on molecular ordering. TGA demonstrated a significant improvement in thermal stability, with the onset temperature rising from 185 °C (pure PU) to 212 °C and the degradation temperature increasing from 370 °C to 425 °C for the 50% blend, attributed to the rigid structure of PLA and MXene’s stabilizing effect. Shape memory testing revealed that the 30% PLA/PU/MXene blend achieved the best shape fixity and recovery with optimal performance, whereas higher PLA content diminished shape memory behavior.