## 6 Prospects and Emerging Trends  
In recent times, there has been a significant surge in the scientific community's interest in SMPs and related composites (SMPCs), as evidenced by the upward trend in the number of scientific publications over the past few decades, as illustrated in Figure 31. The extensive research on SMPs and SMPCs, focusing on new mechanisms, fabrication methods, fillers, and responsiveness to stimuli, highlights their potential for a plethora of future applications. The successful implementation of SMPCs in future prospects depends on their ability to adopt new mechanisms and environments effectively, overcoming challenges such as lack of thermal stability, reduced mechanical strength, brittleness, material degradation due to aging, and associated production costs [324,325]. This review outlines some areas where a surge in research is anticipated. 4D printing is a relatively new prototyping technology that can replace traditional mechanical components in modern engineering equipment and biomedical devices, which can change their certain shapes [325]. Although 4D SMPCs have attracted significant interest, there is still a need to acquire substantial knowledge on better reprogramming, limitations in the printing process, and the ability to perform multi-material printing. While one-way 4D SMPCs have shown excellent properties, research focused on multi-way SMPs is also required. Furthermore, developing 4D-printed SMP-based sustainable composites for biomedical devices is crucial to realizing the true importance of this novel technology [326]. The addition of nanofillers significantly improves the properties of SMPCs. The composition, concentration, shape, and distribution patterns of the fillers determine their interactions with the polymer matrices. However, adding higher fractions of additives may interfere with the performance of SMPCs. Therefore, novel SMPCs need to be designed with a delicate balance between properties and additives, focusing on intended applications [325]. While SMPC-based electronics, storage devices, and energy harvesting devices are popular, there is room for improvement for their commercial applications. Fabricating materials with broad transition temperature changes, deploying two-way or multiple-way SMEs, and developing new fabrication methods utilizing advanced structures combined with different actuation mechanisms will pave the way for their commercial availability [30]. Future research is expected to focus more on remote actuation techniques rather than traditional techniques to achieve safer and better control over the recovery process. This can be achieved by designing composites with embedded fillers responsive to light and ultrasound, further enhanced by burrowing mechanisms from nature [30]. In extreme applications such as aerospace engineering, the mechanical strength of SMPCs can be compromised during thermal processes since they could be exposed to temperatures exceeding the glass transition temperatures (T\({}_{\text{g}}\)). Therefore, enhancing mechanical properties that can withstand higher temperature changes is crucial [327]. To further optimize and tailor the properties of SMPNCs, the incorporation of machine learning (ML) and computational simulations offers transformative potential to predict, optimize, and design material properties with unprecedented accuracy and efficiency [328]. By utilizing large datasets of material behavior, ML algorithms can identify complex correlations between nanocomposite compositions, external stimuli, and shape-memory effects. This data-driven approach can significantly reduce the time and cost associated with experimental processes, enabling the rapid prototyping of customized SMPNCs [329]. Figure 31: Illustration of the yearly quantity of scientific publications since 2000, obtained by employing the search phrases “shape-memory polymer”, “shape-memory polymer composites”, and “shape-memory polymer nanocomposites”. The data analysis was conducted with the Scopus search system on 29 January 2024.